mirror of
https://github.com/berkeleydb/je.git
synced 2024-11-13 00:56:25 +00:00
Initial import.
This commit is contained in:
Greg Burd
commit
10c9f34f67
2932 changed files with 905002 additions and 0 deletions
458
FindBugsExclude.xml
Normal file
458
FindBugsExclude.xml
Normal file
|
|
@ -0,0 +1,458 @@
|
|||
<!-- The excluded FindBugs warnings listed below are "known" and "ok".
|
||||
Run FindBugs with this as an exclude file. For example:
|
||||
|
||||
findbugs -textui -exclude FindBugsExclude.xml je.jar
|
||||
|
||||
-->
|
||||
<FindBugsFilter>
|
||||
<Match class="com.sleepycat.collections.BlockIterator">
|
||||
<BugCode name="REC" />
|
||||
<Method name="add"/>
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.compat.DbCompat">
|
||||
<BugCode name="MS" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.bind.serial.SerialOutput">
|
||||
<BugCode name="MS" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.Database">
|
||||
<BugCode name="IS" />
|
||||
<Field name="handleLocker" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.DatabaseEntry">
|
||||
<BugCode name="MS" />
|
||||
<Field name="MAX_DUMP_BYTES" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.Environment">
|
||||
<BugCode name="UG" />
|
||||
<Method name="getMutableConfig"/>
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.dbi.DatabaseImpl">
|
||||
<BugCode name="MS" />
|
||||
<Field name="forceTreeWalkForTruncateAndRemove" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.dbi.MemoryBudget">
|
||||
<BugCode name="MS" />
|
||||
<Field name="CLEANUP_DONE" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.dbi.MemoryBudget">
|
||||
<BugCode name="MS" />
|
||||
<Field name="DEBUG_ADMIN" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.dbi.MemoryBudget">
|
||||
<BugCode name="MS" />
|
||||
<Field name="DEBUG_LOCK" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.dbi.MemoryBudget">
|
||||
<BugCode name="MS" />
|
||||
<Field name="DEBUG_TXN" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.dbi.MemoryBudget">
|
||||
<BugCode name="MS" />
|
||||
<Field name="DEBUG_TREEADMIN" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.dbi.MemoryBudget">
|
||||
<BugCode name="MS" />
|
||||
<Field name="DEBUG_TREE" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.persist.impl.PersistCatalog">
|
||||
<BugCode name="MS" />
|
||||
<Field name="expectNoClassChanges" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.persist.model.ClassEnhancer">
|
||||
<BugCode name="RV" />
|
||||
<Method name="enhanceFile"/>
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.txn.LockType">
|
||||
<BugCode name="IC" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.log.LogEntryType">
|
||||
<BugCode name="MS" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.log.LogUtils">
|
||||
<BugCode name="MS" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.tree.BIN">
|
||||
<BugCode name="Eq" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.tree.DIN">
|
||||
<BugCode name="Eq" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.tree.DBIN">
|
||||
<BugCode name="Eq" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.tree.DBINReference">
|
||||
<BugCode name="Eq" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.collections.StoredMapEntry">
|
||||
<BugCode name="Eq" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.log.StatsFileReader$LogEntryTypeComparator" >
|
||||
<BugCode name="Se" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.log.FileManager">
|
||||
<BugCode name="ST" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.log.FileManager">
|
||||
<BugCode name="MS" />
|
||||
<Field name="WRITE_COUNT" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.log.FileManager">
|
||||
<BugCode name="MS" />
|
||||
<Field name="STOP_ON_WRITE_COUNT" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.log.FileManager">
|
||||
<BugCode name="MS" />
|
||||
<Field name="N_BAD_WRITES" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.log.FileManager">
|
||||
<BugCode name="MS" />
|
||||
<Field name="THROW_ON_WRITE" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.persist.impl.Format">
|
||||
<BugCode name="ST" />
|
||||
<Method name="getReader"/>
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.log.ScavengerFileReader">
|
||||
<BugCode name="NP" />
|
||||
<Method name="resyncReader"/>
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.persist.impl.Evolver">
|
||||
<BugCode name="NP" />
|
||||
<Method name="evolveRequiredKeyField"/>
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.persist.impl.Evolver">
|
||||
<BugCode name="NP" />
|
||||
<Method name="evolveFormatInternal"/>
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.dbi.EnvironmentImpl">
|
||||
<BugCode name="ST" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.dbi.EnvironmentImpl">
|
||||
<BugCode name="ICAST" />
|
||||
<Method name="updateBackgroundWrites"/>
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.dbi.EnvironmentImpl">
|
||||
<BugCode name="SWL" />
|
||||
<Method name="sleepAfterBackgroundIO"/>
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.TransactionStats$Active">
|
||||
<BugCode name="SIC" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.evictor.Evictor">
|
||||
<BugCode name="IS2" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.evictor.Evictor">
|
||||
<BugCode name="IS" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.latch.SharedLatch">
|
||||
<BugCode name="PS" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.latch.LatchImpl">
|
||||
<BugCode name="IS" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.latch.SharedLatchImpl">
|
||||
<BugCode name="IS" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.latch.Latch">
|
||||
<BugCode name="IS2" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.latch.Latch">
|
||||
<BugCode name="Wa" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.latch.Java5LatchImpl">
|
||||
<BugCode name="IMSE" />
|
||||
<Method name="doRelease" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.latch.Latch">
|
||||
<BugCode name="IMSE" />
|
||||
<Method name="doRelease" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.latch.Java5SharedLatchImpl" >
|
||||
<BugCode name="SnVI" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.latch.Java5SharedLatchImpl">
|
||||
<BugCode name="IMSE" />
|
||||
<Method name="release" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.latch.SharedLatch">
|
||||
<BugCode name="IMSE" />
|
||||
<Method name="release" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.latch.Java5SharedLatchImpl">
|
||||
<BugCode name="UL" />
|
||||
<Method name="acquireExclusive" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.latch.Java5SharedLatchImpl">
|
||||
<BugCode name="UL" />
|
||||
<Method name="acquireShared" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.latch.SharedLatch">
|
||||
<BugCode name="UL" />
|
||||
<Method name="acquireExclusive" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.latch.SharedLatch">
|
||||
<BugCode name="UL" />
|
||||
<Method name="acquireShared" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.cleaner.Cleaner">
|
||||
<BugCode name="IS2" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.cleaner.FileProcessor">
|
||||
<BugCode name="IS" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.cleaner.UtilizationProfile">
|
||||
<BugCode name="IS" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.recovery.Checkpointer">
|
||||
<BugCode name="IS2" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.recovery.Checkpointer">
|
||||
<BugCode name="ICAST" />
|
||||
<Method name="isRunnable" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.recovery.Checkpointer">
|
||||
<BugCode name="IS" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.recovery.RecoveryManager">
|
||||
<BugCode name="REC" />
|
||||
<Method name="readINsAndTrackIds"/>
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.recovery.RecoveryManager">
|
||||
<BugCode name="REC" />
|
||||
<Method name="redoLNs"/>
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.txn.Txn">
|
||||
<BugCode name="IS2" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.txn.Txn">
|
||||
<BugCode name="IS" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.collections.StoredMap">
|
||||
<BugCode name="IS2" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.Sequence">
|
||||
<BugCode name="IS2" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.Sequence">
|
||||
<BugCode name="IS" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.incomp.INCompressor">
|
||||
<BugCode name="IS,IS2,BC" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.tree.Key">
|
||||
<BugCode name="MS" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.tree.IN">
|
||||
<BugCode name="MS" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.tree.Tree">
|
||||
<BugCode name="DMI" />
|
||||
<Method name="validateINList" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.tree.Tree">
|
||||
<BugCode name="NP" />
|
||||
<Method name="deleteDupSubtree" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.tree.Tree">
|
||||
<BugCode name="NP" />
|
||||
<Method name="splitRoot" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.tree.Tree">
|
||||
<BugCode name="NP" />
|
||||
<Method name="searchSplitsAllowed" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.txn.Txn">
|
||||
<BugCode name="MS" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.collections.StoredIterator">
|
||||
<BugCode name="RV" />
|
||||
<Method name="reset"/>
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.utilint.DaemonThread">
|
||||
<BugCode name="RV" />
|
||||
<Method name="checkErrorListener"/>
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.collections.DataView">
|
||||
<BugCode name="DE" />
|
||||
<Method name="join"/>
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.utilint.TracerFormatter">
|
||||
<BugCode name="DE" />
|
||||
<Method name="format"/>
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.incomp.INCompressor">
|
||||
<BugCode name="RCN" />
|
||||
<Method name="searchForBIN"/>
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.tree.Tree">
|
||||
<BugCode name="RCN" />
|
||||
<Method name="getNextBinInternal"/>
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.log.FSyncManager$FSyncGroup">
|
||||
<BugCode name="NN" />
|
||||
<Method name="wakeupOne"/>
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.txn.LockManager">
|
||||
<BugCode name="NN" />
|
||||
<Method name="release"/>
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.utilint.DaemonThread">
|
||||
<BugCode name="UW" />
|
||||
<Method name="run"/>
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.util.DbRunAction">
|
||||
<BugCode name="REC" />
|
||||
<Method name="main"/>
|
||||
</Match>
|
||||
|
||||
<Match classregex="com.sleepycat.je.util.*" >
|
||||
<BugCode name="Dm" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.asm.signature.SignatureWriter" >
|
||||
<BugCode name="IM" />
|
||||
<Method name="endArguments" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.asm.ClassReader" >
|
||||
<BugCode name="Bx" />
|
||||
<Method name="readAnnotationValue" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.asm.ClassReader" >
|
||||
<BugCode name="Bx" />
|
||||
<Method name="readConst" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.bind.serial.StoredClassCatalog$ClassInfo" >
|
||||
<BugCode name="SnVI" />
|
||||
</Match>
|
||||
|
||||
<Match classregex="com.sleepycat.persist.impl.*" >
|
||||
<BugCode name="SnVI" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.persist.impl.ComplexFormat$SkipFieldReader">
|
||||
<BugCode name="Se" />
|
||||
<Field name="endField" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.persist.impl.EnumFormat" >
|
||||
<BugCode name="Se" />
|
||||
<Field name="values" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.persist.impl.FieldInfo" >
|
||||
<BugCode name="Se" />
|
||||
<Field name="cls" />
|
||||
</Match>
|
||||
|
||||
<Match classregex=".*" >
|
||||
<BugCode name="EI,EI2,CD" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.asm.Handler" >
|
||||
<BugCode name="UrF" />
|
||||
<Field name="desc" />
|
||||
</Match>
|
||||
|
||||
<Match class="com.sleepycat.je.dbi.EnvironmentImpl" >
|
||||
<BugCode name="UrF" />
|
||||
<Field name="lockoutTimeout" />
|
||||
</Match>
|
||||
|
||||
<!-- Match all doublecheck violations in these methods of "AnotherClass".
|
||||
<Match class="com.foobar.AnotherClass">
|
||||
<Or>
|
||||
<Method name="nonOverloadedMethod" />
|
||||
<Method name="frob" params="int,java.lang.String" returns="void" />
|
||||
<Method name="blat" params="" returns="boolean" />
|
||||
</Or>
|
||||
<BugCode name="DC" />
|
||||
</Match>
|
||||
-->
|
||||
</FindBugsFilter>
|
||||
76
LICENSE
Normal file
76
LICENSE
Normal file
|
|
@ -0,0 +1,76 @@
|
|||
Copyright (C) 2002, 2016, Oracle and/or its affiliates. All rights reserved.
|
||||
|
||||
Licensed under the Apache License, Version 2.0 (the "License") reproduced below or available at:
|
||||
|
||||
http://www.apache.org/licenses/LICENSE-2.0
|
||||
|
||||
Unless required by applicable law or agreed to in writing, software
|
||||
distributed under the License is distributed on an "AS IS" BASIS,
|
||||
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
||||
See the License for the specific language governing permissions and
|
||||
limitations under the License.
|
||||
Apache License
|
||||
Version 2.0, January 2004
|
||||
http://www.apache.org/licenses/
|
||||
TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
|
||||
1. Definitions.
|
||||
"License" shall mean the terms and conditions for use, reproduction, and distribution as defined by Sections 1 through 9 of this document.
|
||||
"Licensor" shall mean the copyright owner or entity authorized by the copyright owner that is granting the License.
|
||||
"Legal Entity" shall mean the union of the acting entity and all other entities that control, are controlled by, or are under common control with that entity. For the purposes of this definition, "control" means (i) the power, direct or indirect, to cause the direction or management of such entity, whether by contract or otherwise, or (ii) ownership of fifty percent (50%) or more of the outstanding shares, or (iii) beneficial ownership of such entity.
|
||||
"You" (or "Your") shall mean an individual or Legal Entity exercising permissions granted by this License.
|
||||
"Source" form shall mean the preferred form for making modifications, including but not limited to software source code, documentation source, and configuration files.
|
||||
"Object" form shall mean any form resulting from mechanical transformation or translation of a Source form, including but not limited to compiled object code, generated documentation, and conversions to other media types.
|
||||
"Work" shall mean the work of authorship, whether in Source or Object form, made available under the License, as indicated by a copyright notice that is included in or attached to the work (an example is provided in the Appendix below).
|
||||
"Derivative Works" shall mean any work, whether in Source or Object form, that is based on (or derived from) the Work and for which the editorial revisions, annotations, elaborations, or other modifications represent, as a whole, an original work of authorship. For the purposes of this License, Derivative Works shall not include works that remain separable from, or merely link (or bind by name) to the interfaces of, the Work and Derivative Works thereof.
|
||||
"Contribution" shall mean any work of authorship, including the original version of the Work and any modifications or additions to that Work or Derivative Works thereof, that is intentionally submitted to Licensor for inclusion in the Work by the copyright owner or by an individual or Legal Entity authorized to submit on behalf of the copyright owner. For the purposes of this definition, "submitted" means any form of electronic, verbal, or written communication sent to the Licensor or its representatives, including but not limited to communication on electronic mailing lists, source code control systems, and issue tracking systems that are managed by, or on behalf of, the Licensor for the purpose of discussing and improving the Work, but excluding communication that is conspicuously marked or otherwise designated in writing by the copyright owner as "Not a Contribution."
|
||||
"Contributor" shall mean Licensor and any individual or Legal Entity on behalf of whom a Contribution has been received by Licensor and subsequently incorporated within the Work.
|
||||
2. Grant of Copyright License. Subject to the terms and conditions of this License, each Contributor hereby grants to You a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare Derivative Works of, publicly display, publicly perform, sublicense, and distribute the Work and such Derivative Works in Source or Object form.
|
||||
3. Grant of Patent License. Subject to the terms and conditions of this License, each Contributor hereby grants to You a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable (except as stated in this section) patent license to make, have made, use, offer to sell, sell, import, and otherwise transfer the Work, where such license applies only to those patent claims licensable by such Contributor that are necessarily infringed by their Contribution(s) alone or by combination of their Contribution(s) with the Work to which such Contribution(s) was submitted. If You institute patent litigation against any entity (including a cross-claim or counterclaim in a lawsuit) alleging that the Work or a Contribution incorporated within the Work constitutes direct or contributory patent infringement, then any patent licenses granted to You under this License for that Work shall terminate as of the date such litigation is filed.
|
||||
4. Redistribution. You may reproduce and distribute copies of the Work or Derivative Works thereof in any medium, with or without modifications, and in Source or Object form, provided that You meet the following conditions:
|
||||
1. You must give any other recipients of the Work or Derivative Works a copy of this License; and
|
||||
2. You must cause any modified files to carry prominent notices stating that You changed the files; and
|
||||
3. You must retain, in the Source form of any Derivative Works that You distribute, all copyright, patent, trademark, and attribution notices from the Source form of the Work, excluding those notices that do not pertain to any part of the Derivative Works; and
|
||||
4. If the Work includes a "NOTICE" text file as part of its distribution, then any Derivative Works that You distribute must include a readable copy of the attribution notices contained within such NOTICE file, excluding those notices that do not pertain to any part of the Derivative Works, in at least one of the following places: within a NOTICE text file distributed as part of the Derivative Works; within the Source form or documentation, if provided along with the Derivative Works; or, within a display generated by the Derivative Works, if and wherever such third-party notices normally appear. The contents of the NOTICE file are for informational purposes only and do not modify the License. You may add Your own attribution notices within Derivative Works that You distribute, alongside or as an addendum to the NOTICE text from the Work, provided that such additional attribution notices cannot be construed as modifying the License.
|
||||
|
||||
You may add Your own copyright statement to Your modifications and may provide additional or different license terms and conditions for use, reproduction, or distribution of Your modifications, or for any such Derivative Works as a whole, provided Your use, reproduction, and distribution of the Work otherwise complies with the conditions stated in this License.
|
||||
5. Submission of Contributions. Unless You explicitly state otherwise, any Contribution intentionally submitted for inclusion in the Work by You to the Licensor shall be under the terms and conditions of this License, without any additional terms or conditions. Notwithstanding the above, nothing herein shall supersede or modify the terms of any separate license agreement you may have executed with Licensor regarding such Contributions.
|
||||
6. Trademarks. This License does not grant permission to use the trade names, trademarks, service marks, or product names of the Licensor, except as required for reasonable and customary use in describing the origin of the Work and reproducing the content of the NOTICE file.
|
||||
7. Disclaimer of Warranty. Unless required by applicable law or agreed to in writing, Licensor provides the Work (and each Contributor provides its Contributions) on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied, including, without limitation, any warranties or conditions of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A PARTICULAR PURPOSE. You are solely responsible for determining the appropriateness of using or redistributing the Work and assume any risks associated with Your exercise of permissions under this License.
|
||||
8. Limitation of Liability. In no event and under no legal theory, whether in tort (including negligence), contract, or otherwise, unless required by applicable law (such as deliberate and grossly negligent acts) or agreed to in writing, shall any Contributor be liable to You for damages, including any direct, indirect, special, incidental, or consequential damages of any character arising as a result of this License or out of the use or inability to use the Work (including but not limited to damages for loss of goodwill, work stoppage, computer failure or malfunction, or any and all other commercial damages or losses), even if such Contributor has been advised of the possibility of such damages.
|
||||
9. Accepting Warranty or Additional Liability. While redistributing the Work or Derivative Works thereof, You may choose to offer, and charge a fee for, acceptance of support, warranty, indemnity, or other liability obligations and/or rights consistent with this License. However, in accepting such obligations, You may act only on Your own behalf and on Your sole responsibility, not on behalf of any other Contributor, and only if You agree to indemnify, defend, and hold each Contributor harmless for any liability incurred by, or claims asserted against, such Contributor by reason of your accepting any such warranty or additional liability.
|
||||
END OF TERMS AND CONDITIONS
|
||||
|
||||
|
||||
ADDITIONAL THIRD PARTY NOTICES:
|
||||
|
||||
|
||||
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
|
||||
/***
|
||||
* ASM: a very small and fast Java bytecode manipulation framework
|
||||
* Copyright (c) 2000-2005 INRIA, France Telecom
|
||||
* All rights reserved.
|
||||
*
|
||||
* Redistribution and use in source and binary forms, with or without
|
||||
* modification, are permitted provided that the following conditions
|
||||
* are met:
|
||||
* 1. Redistributions of source code must retain the above copyright
|
||||
* notice, this list of conditions and the following disclaimer.
|
||||
* 2. Redistributions in binary form must reproduce the above copyright
|
||||
* notice, this list of conditions and the following disclaimer in the
|
||||
* documentation and/or other materials provided with the distribution.
|
||||
* 3. Neither the name of the copyright holders nor the names of its
|
||||
* contributors may be used to endorse or promote products derived from
|
||||
* this software without specific prior written permission.
|
||||
*
|
||||
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
|
||||
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
||||
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
||||
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
|
||||
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
|
||||
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
|
||||
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
|
||||
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
|
||||
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
|
||||
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
|
||||
* THE POSSIBILITY OF SUCH DAMAGE.
|
||||
*/
|
||||
5
README
Normal file
5
README
Normal file
|
|
@ -0,0 +1,5 @@
|
|||
Oracle: Berkeley DB, Java Edition 7.5.11: 2017-10-31 09:36:36 UTC
|
||||
|
||||
This is Berkeley DB, Java Edition, version 7.5.11 from
|
||||
Oracle. To view the release and installation documentation, load
|
||||
the distribution file docs/index.html into your web browser.
|
||||
16
ant/PrintBootClassPath.java
Normal file
16
ant/PrintBootClassPath.java
Normal file
|
|
@ -0,0 +1,16 @@
|
|||
/*-
|
||||
* See the file LICENSE for redistribution information.
|
||||
*
|
||||
* Copyright (c) 2011, 2016 Oracle and/or its affiliates. All rights reserved.
|
||||
*
|
||||
*/
|
||||
|
||||
/**
|
||||
* Print the value of the "sun.boot.class.path" system property, which is the
|
||||
* boot classpath for the Oracle Java virtual machine.
|
||||
*/
|
||||
public class PrintBootClassPath {
|
||||
public static void main(String[] args) {
|
||||
System.out.println(System.getProperty("sun.boot.class.path"));
|
||||
}
|
||||
}
|
||||
121
ant/compile.xml
Normal file
121
ant/compile.xml
Normal file
|
|
@ -0,0 +1,121 @@
|
|||
<?xml version="1.0"?>
|
||||
|
||||
<project name="compile" default="compile" basedir=".">
|
||||
<description>Shared compile target.</description>
|
||||
|
||||
<import file="${basedir}/build-common.xml"/>
|
||||
|
||||
<property name="include" value="com/sleepycat/**/*.java"/>
|
||||
<property name="exclude1" value="com/sleepycat/**/jca/**/*.java"/>
|
||||
<property name="exclude3" value="com/sleepycat/je/jmx/plugin/*.java"/>
|
||||
<property name="exclude4" value="com/sleepycat/je/rep/jmx/plugin/*.java"/>
|
||||
|
||||
<!--
|
||||
The sourcepath="" line must be specified in that way to clear out the field
|
||||
and ensure that excludes takes effect.
|
||||
|
||||
jdk.source.version and jdk.target.version can be set to 1.6 to
|
||||
compile for Java 6 source and bytecode, but this won't enforce the
|
||||
runtime library. Use the compile-java6 target (below) instead when
|
||||
building a release.
|
||||
-->
|
||||
<target name="compile" depends="get-jdk-source-boot-classpath">
|
||||
<javac sourcepath=""
|
||||
srcdir="${srcdir}"
|
||||
includes="${include}"
|
||||
excludes="${exclude1}, ${exclude2}, ${exclude3}, ${exclude4},
|
||||
${exclude5}"
|
||||
destdir="${destdir}"
|
||||
classpathref="compile.classpath"
|
||||
debug="${build.debug}"
|
||||
deprecation="${build.deprecation}"
|
||||
optimize="on"
|
||||
includeantruntime="true"
|
||||
source="${jdk.source.version}"
|
||||
target="${jdk.target.version}"
|
||||
bootclasspath="${jdk.source.boot.classpath}">
|
||||
<!--
|
||||
<compilerarg value="-Xlint:unchecked"/>
|
||||
-->
|
||||
</javac>
|
||||
</target>
|
||||
|
||||
<!--
|
||||
Compile for Java 6 source, bytecode and runtime libraries. This uses the
|
||||
approach from the "Cross-Compilation Example" in the man page for javac,
|
||||
version 1.7. The jdk6.home property must be set to use this target.
|
||||
-->
|
||||
<target name="compile-java6" depends="get-jdk6-boot-classpath">
|
||||
<javac sourcepath=""
|
||||
srcdir="${srcdir}"
|
||||
includes="${include}"
|
||||
excludes="${exclude1}, ${exclude2}, ${exclude3}, ${exclude4},
|
||||
${exclude5}"
|
||||
destdir="${destdir}"
|
||||
classpathref="compile.classpath"
|
||||
debug="${build.debug}"
|
||||
deprecation="${build.deprecation}"
|
||||
optimize="on"
|
||||
includeantruntime="true"
|
||||
source="1.6"
|
||||
target="1.6"
|
||||
bootclasspath="${jdk6.boot.classpath}"
|
||||
extdirs="">
|
||||
<!--
|
||||
<compilerarg value="-Xlint:unchecked"/>
|
||||
-->
|
||||
</javac>
|
||||
</target>
|
||||
|
||||
<!--
|
||||
Store the Java 8 boot classpath in jdk.source.boot.classpath,
|
||||
computing it by calling PrintBootClassPath using the Java 8 JVM
|
||||
available in jdk8.home, if set.
|
||||
-->
|
||||
<target name="get-jdk-source-boot-classpath"
|
||||
depends="compile-print-boot-classpath"
|
||||
if="jdk8.home">
|
||||
<java fork="yes"
|
||||
jvm="${jdk8.home}/bin/java"
|
||||
failonerror="true"
|
||||
logerror="true"
|
||||
classname="PrintBootClassPath"
|
||||
classpath="${builddir}/tmp"
|
||||
outputproperty="jdk.source.boot.classpath"/>
|
||||
</target>
|
||||
|
||||
<!--
|
||||
Store the Java 6 boot classpath in jdk6.boot.classpath, computing it
|
||||
by calling PrintBootClassPath using the Java 6 JVM available in
|
||||
jdk6.home, if set.
|
||||
-->
|
||||
<target name="get-jdk6-boot-classpath"
|
||||
depends="compile-print-boot-classpath"
|
||||
if="jdk6.home">
|
||||
<java fork="yes"
|
||||
jvm="${jdk6.home}/bin/java"
|
||||
failonerror="true"
|
||||
logerror="true"
|
||||
classname="PrintBootClassPath"
|
||||
classpath="${builddir}/tmp"
|
||||
outputproperty="jdk6.boot.classpath"/>
|
||||
</target>
|
||||
|
||||
<!--
|
||||
Compile the PrintBootClassPath utility class, with 1.6 as the
|
||||
target, so that we can use this with the Java 6 JVM.
|
||||
-->
|
||||
<target name="compile-print-boot-classpath">
|
||||
<mkdir dir="${builddir}/tmp"/>
|
||||
<javac srcdir="${basedir}/ant"
|
||||
includes="PrintBootClassPath.java"
|
||||
destdir="${builddir}/tmp"
|
||||
includeantruntime="false"
|
||||
debug="${build.debug}"
|
||||
source="1.6"
|
||||
target="1.6">
|
||||
<!-- Ignore boot classpath warnings -->
|
||||
<compilerarg value="-Xlint:-options"/>
|
||||
</javac>
|
||||
</target>
|
||||
</project>
|
||||
1187
ant/internal.xml
Normal file
1187
ant/internal.xml
Normal file
File diff suppressed because it is too large
Load diff
21
build-common.xml
Normal file
21
build-common.xml
Normal file
|
|
@ -0,0 +1,21 @@
|
|||
<!--
|
||||
Common definitions imported by build.xml, ant/compile.xml, etc.
|
||||
-->
|
||||
<project basedir=".">
|
||||
<property name="srcdir" value="${basedir}/src"/>
|
||||
<property name="builddir" value="${basedir}/build"/>
|
||||
<property name="destdir" value="${builddir}/classes"/>
|
||||
<property name="libdir" value="${builddir}/lib"/>
|
||||
<property name="extlibdir" value="${basedir}/extlib"/>
|
||||
<property name="ivy.lib.dir" value="${extlibdir}"/>
|
||||
|
||||
<property name="junit.jarfile" value="${extlibdir}/junit-4.10.jar"/>
|
||||
<property name="hamcrest.jarfile" value="${extlibdir}/hamcrest-core-1.1.jar"/>
|
||||
|
||||
<property name="build.debug" value="on"/>
|
||||
<property name="build.deprecation" value="off"/>
|
||||
|
||||
<!-- The JDK source and target versions for compiles and javadoc -->
|
||||
<property name="jdk.source.version" value="1.8"/>
|
||||
<property name="jdk.target.version" value="1.8"/>
|
||||
</project>
|
||||
4
dist/build.properties
vendored
Normal file
4
dist/build.properties
vendored
Normal file
|
|
@ -0,0 +1,4 @@
|
|||
release.version=7.5.11
|
||||
release.numeric.version=7.5.11
|
||||
release.major=7
|
||||
release.minor=5
|
||||
BIN
docs/GettingStartedGuide/BerkeleyDB-JE-GSG.pdf
Normal file
BIN
docs/GettingStartedGuide/BerkeleyDB-JE-GSG.pdf
Normal file
Binary file not shown.
214
docs/GettingStartedGuide/Cursors.html
Normal file
214
docs/GettingStartedGuide/Cursors.html
Normal file
|
|
@ -0,0 +1,214 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Chapter 9. Using Cursors</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="baseapi.html" title="Part II. Programming with the Base API" />
|
||||
<link rel="prev" href="dbtUsage.html" title="Database Record Example" />
|
||||
<link rel="next" href="Positioning.html" title="Getting Records Using the Cursor" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Chapter 9. Using Cursors</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="dbtUsage.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Part II. Programming with the Base API</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="Positioning.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="chapter" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title"><a id="Cursors"></a>Chapter 9. Using Cursors</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="toc">
|
||||
<p>
|
||||
<b>Table of Contents</b>
|
||||
</p>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="Cursors.html#openCursor">Opening and Closing Cursors</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="Positioning.html">Getting Records Using the Cursor</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="Positioning.html#diskorderedcursors">Disk Ordered Cursors</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="Positioning.html#cursorsearch">Searching for Records</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="Positioning.html#getdups">Working with Duplicate Records</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="PutEntryWCursor.html">Putting Records Using Cursors</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="DeleteEntryWCursor.html">Deleting Records Using Cursors</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="ReplacingEntryWCursor.html">Replacing Records Using Cursors</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="cursorUsage.html">Cursor Example</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</div>
|
||||
<p>
|
||||
Cursors provide a mechanism by which you can iterate over the records in a
|
||||
database. Using cursors, you can get, put, and delete database records. If
|
||||
a database allows duplicate records, then cursors are
|
||||
|
||||
<span>the only mechanism by
|
||||
which you can access anything other than the first duplicate for a given
|
||||
key.</span>
|
||||
|
||||
|
||||
</p>
|
||||
<p>
|
||||
This chapter introduces cursors. It explains how to open and close them, how
|
||||
to use them to modify databases, and how to use them with duplicate records.
|
||||
</p>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="openCursor"></a>Opening and Closing Cursors</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
To use a cursor, you must open it using the <code class="methodname">Database.openCursor()</code>
|
||||
method. When you open a
|
||||
cursor, you can optionally pass it a <code class="classname">CursorConfig</code>
|
||||
object to set cursor properties.
|
||||
<span>
|
||||
The cursor properties that you can set allows you to
|
||||
determine whether the cursor will perform committed or
|
||||
uncommitted reads. See the
|
||||
<em class="citetitle">Berkeley DB, Java Edition Getting Started with Transaction Processing</em> guide for more
|
||||
information.
|
||||
</span>
|
||||
|
||||
</p>
|
||||
<p>For example:</p>
|
||||
<a id="je_cursor1"></a>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.je.Cursor;
|
||||
import com.sleepycat.je.Database;
|
||||
import com.sleepycat.je.DatabaseException;
|
||||
import com.sleepycat.je.Environment;
|
||||
|
||||
import java.io.File;
|
||||
|
||||
...
|
||||
Environment myDbEnvironment = null;
|
||||
Database myDatabase = null;
|
||||
Cursor myCursor = null;
|
||||
|
||||
try {
|
||||
myDbEnvironment = new Environment(new File("/export/dbEnv"), null);
|
||||
myDatabase = myDbEnvironment.openDatabase(null, "myDB", null);
|
||||
|
||||
myCursor = myDatabase.openCursor(null, null);
|
||||
} catch (DatabaseException dbe) {
|
||||
// Exception handling goes here ...
|
||||
}</pre>
|
||||
<p>
|
||||
To close the cursor, call the <code class="methodname">Cursor.close()</code>
|
||||
method. Note that if you close a database that has cursors open in it,
|
||||
then it will throw an exception and close any open cursors for you.
|
||||
For best results, close your cursors from within a
|
||||
<code class="literal">finally</code> block. However, it is recommended that you always close all cursor handles immediately after their use to ensure concurrency and to release resources such as page locks.
|
||||
<span></span>
|
||||
</p>
|
||||
<a id="je_cursor2"></a>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.je.Cursor;
|
||||
import com.sleepycat.je.Database;
|
||||
import com.sleepycat.je.Environment;
|
||||
|
||||
...
|
||||
try {
|
||||
...
|
||||
} catch ... {
|
||||
} finally {
|
||||
try {
|
||||
if (myCursor != null) {
|
||||
myCursor.close();
|
||||
}
|
||||
|
||||
if (myDatabase != null) {
|
||||
myDatabase.close();
|
||||
}
|
||||
|
||||
if (myDbEnvironment != null) {
|
||||
myDbEnvironment.close();
|
||||
}
|
||||
} catch(DatabaseException dbe) {
|
||||
System.err.println("Error in close: " + dbe.toString());
|
||||
}
|
||||
} </pre>
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="dbtUsage.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="baseapi.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="Positioning.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Database Record Example </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Getting Records Using the Cursor</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
157
docs/GettingStartedGuide/DBAdmin.html
Normal file
157
docs/GettingStartedGuide/DBAdmin.html
Normal file
|
|
@ -0,0 +1,157 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Administrative Methods</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="databases.html" title="Chapter 7. Databases" />
|
||||
<link rel="prev" href="dbprops.html" title="Database Properties" />
|
||||
<link rel="next" href="dbUsage.html" title="Database Example" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Administrative Methods</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="dbprops.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 7. Databases</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="dbUsage.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="DBAdmin"></a>Administrative Methods</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
Both the <code class="classname">Environment</code> and
|
||||
<code class="classname">Database</code> classes provide methods that are useful
|
||||
for manipulating databases. These methods are:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
<code class="methodname">Database.getDatabaseName()</code>
|
||||
</p>
|
||||
<p>Returns the database's name.</p>
|
||||
<a id="je_db3.1"></a>
|
||||
<pre class="programlisting">String dbName = myDatabase.getDatabaseName();</pre>
|
||||
<span>
|
||||
</span>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="methodname">Database.getEnvironment()</code>
|
||||
</p>
|
||||
<p>Returns the <code class="classname">Environment</code> that contains this database.</p>
|
||||
<a id="je_db4"></a>
|
||||
<pre class="programlisting">Environment theEnv = myDatabase.getEnvironment();</pre>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="methodname">Database.preload()</code>
|
||||
</p>
|
||||
<p>Preloads the database into the in-memory cache. Optionally takes
|
||||
a <code class="literal">long</code> that identifies the maximum number of bytes to load into the
|
||||
cache. If this parameter is not supplied, the maximum memory usage
|
||||
allowed by the evictor thread is used.
|
||||
</p>
|
||||
<a id="je_db6"></a>
|
||||
<pre class="programlisting">myDatabase.preload(1048576l); // 1024*1024</pre>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="methodname">Environment.getDatabaseNames()</code>
|
||||
</p>
|
||||
<p>Returns a list of Strings of all the databases contained by the
|
||||
environment.</p>
|
||||
<a id="je_db7"></a>
|
||||
<pre class="programlisting">import java.util.List;
|
||||
...
|
||||
List myDbNames = myDbEnv.getDatabaseNames();
|
||||
for(int i=0; i < myDbNames.size(); i++) {
|
||||
System.out.println("Database Name: " + (String)myDbNames.get(i));
|
||||
}</pre>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="methodname">Environment.removeDatabase()</code>
|
||||
</p>
|
||||
<p>Deletes the database. The database must be closed when you
|
||||
perform this action on it.</p>
|
||||
<a id="je_db8"></a>
|
||||
<pre class="programlisting">String dbName = myDatabase.getDatabaseName();
|
||||
myDatabase.close();
|
||||
myDbEnv.removeDatabase(null, dbName);</pre>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="methodname">Environment.renameDatabase()</code>
|
||||
</p>
|
||||
<p>Renames the database. The database must be closed when you
|
||||
perform this action on it.</p>
|
||||
<a id="je_db9"></a>
|
||||
<pre class="programlisting">String oldName = myDatabase.getDatabaseName();
|
||||
String newName = new String(oldName + ".new", "UTF-8");
|
||||
myDatabase.close();
|
||||
myDbEnv.renameDatabase(null, oldName, newName);</pre>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="methodname">Environment.truncateDatabase()</code>
|
||||
</p>
|
||||
<p>
|
||||
Deletes every record in the database and optionally returns the
|
||||
number of records that were deleted. Note that it is much less
|
||||
expensive to truncate a database without counting the number of
|
||||
records deleted than it is to truncate and count.
|
||||
</p>
|
||||
<a id="je_db5"></a>
|
||||
<pre class="programlisting">int numDiscarded =
|
||||
myEnv.truncate(null, // txn handle
|
||||
myDatabase.getDatabaseName(), // database name
|
||||
true); // If true, then the
|
||||
// number of records
|
||||
// deleted are counted.
|
||||
System.out.println("Discarded " + numDiscarded +
|
||||
" records from database " +
|
||||
myDatabase.getDatabaseName()); </pre>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="dbprops.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="databases.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="dbUsage.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Database Properties </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Database Example</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
303
docs/GettingStartedGuide/DBEntry.html
Normal file
303
docs/GettingStartedGuide/DBEntry.html
Normal file
|
|
@ -0,0 +1,303 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Chapter 8. Database Records</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="baseapi.html" title="Part II. Programming with the Base API" />
|
||||
<link rel="prev" href="dbUsage.html" title="Database Example" />
|
||||
<link rel="next" href="usingDbt.html" title="Reading and Writing Database Records" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Chapter 8. Database Records</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="dbUsage.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Part II. Programming with the Base API</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="usingDbt.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="chapter" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title"><a id="DBEntry"></a>Chapter 8. Database Records</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="toc">
|
||||
<p>
|
||||
<b>Table of Contents</b>
|
||||
</p>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="DBEntry.html#usingDbEntry">Using Database Records</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="usingDbt.html">Reading and Writing Database Records</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="usingDbt.html#databaseWrite">Writing Records to the Database</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="usingDbt.html#databaseRead">Getting Records from the Database</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="usingDbt.html#recordDelete">Deleting Records</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="usingDbt.html#datapersist">Data Persistence</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="timetolive.html">Using Time to Live</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="timetolive.html#ttl-specify">Specifying a TTL Value</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="timetolive.html#ttl-update">Updating a TTL Value</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="timetolive.html#ttl-remove">Deleting TTL Expiration</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="bindAPI.html">Using the BIND APIs</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="bindAPI.html#bindPrimitive">Numerical and String Objects</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="bindAPI.html#object2dbt">Serializable Complex Objects</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="bindAPI.html#customTuple">Custom Tuple Bindings</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="comparator.html">Using Comparators</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="comparator.html#writeCompare">Writing Comparators</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="comparator.html#setCompare">Setting Comparators</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="dbtUsage.html">Database Record Example</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</div>
|
||||
<p>
|
||||
JE records contain two parts — a key and some data. Both the key
|
||||
and its corresponding data are
|
||||
encapsulated in
|
||||
<span><code class="classname">DatabaseEntry</code> class objects.</span>
|
||||
|
||||
|
||||
Therefore, to access a JE record, you need two such
|
||||
|
||||
<span>objects,</span> one for the key and
|
||||
one for the data.
|
||||
</p>
|
||||
<p>
|
||||
<code class="classname">DatabaseEntry</code> can hold any kind of data from simple
|
||||
Java primitive types to complex Java objects so long as that data can be
|
||||
represented as a Java <code class="literal">byte</code> array. Note that due to
|
||||
performance considerations, you should not use Java serialization to convert
|
||||
a Java object to a <code class="literal">byte</code> array. Instead, use the Bind APIs
|
||||
to perform this conversion (see
|
||||
<a class="xref" href="bindAPI.html" title="Using the BIND APIs">Using the BIND APIs</a> for more
|
||||
information).
|
||||
</p>
|
||||
<p>
|
||||
This chapter describes how you can convert both Java primitives and Java
|
||||
class objects into and out of <code class="literal">byte</code> arrays. It also
|
||||
introduces storing and retrieving key/value pairs from a database. In
|
||||
addition, this chapter describes how you can use comparators to influence
|
||||
how JE sorts its database records.
|
||||
</p>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="usingDbEntry"></a>Using Database Records</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
Each database record is comprised of two
|
||||
<span><code class="classname">DatabaseEntry</code> objects</span>
|
||||
|
||||
|
||||
— one for the key and another for the data.
|
||||
|
||||
<span>The key and data information are passed to-
|
||||
and returned from JE using
|
||||
<code class="classname">DatabaseEntry</code> objects as <code class="literal">byte</code>
|
||||
arrays. Using <code class="classname">DatabaseEntry</code>s allows JE to
|
||||
change the underlying byte array as well as return multiple values (that
|
||||
is, key and data). Therefore, using <code class="classname">DatabaseEntry</code> instances
|
||||
is mostly an exercise in efficiently moving your keys and your data in
|
||||
and out of <code class="literal">byte</code> arrays.</span>
|
||||
</p>
|
||||
<p>
|
||||
For example, to store a database record where both the key and the
|
||||
data are Java <code class="classname">String</code> objects, you instantiate a
|
||||
pair of <code class="classname">DatabaseEntry</code> objects:
|
||||
</p>
|
||||
<a id="je_dbt1"></a>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.je.DatabaseEntry;
|
||||
|
||||
...
|
||||
|
||||
String aKey = "key";
|
||||
String aData = "data";
|
||||
|
||||
try {
|
||||
DatabaseEntry theKey = new DatabaseEntry(aKey.getBytes("UTF-8"));
|
||||
DatabaseEntry theData = new DatabaseEntry(aData.getBytes("UTF-8"));
|
||||
} catch (Exception e) {
|
||||
// Exception handling goes here
|
||||
}
|
||||
|
||||
// Storing the record is described later in this chapter </pre>
|
||||
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
|
||||
<h3 class="title">Note</h3>
|
||||
<p>
|
||||
Notice that we specify <code class="literal">UTF-8</code> when we retrieve the
|
||||
<code class="literal">byte</code> array from our <code class="classname">String</code>
|
||||
object. Without parameters, <code class="methodname">String.getBytes()</code> uses the
|
||||
Java system's default encoding. You should never use a system's default
|
||||
encoding when storing data in a database because the encoding can change.
|
||||
</p>
|
||||
</div>
|
||||
<p>
|
||||
When the record is retrieved from the database, the method that you
|
||||
use to perform this operation populates two <code class="classname">DatabaseEntry</code>
|
||||
instances for you, one for the key and another for the data. Assuming Java
|
||||
<code class="classname">String</code> objects, you retrieve your data from the
|
||||
<code class="classname">DatabaseEntry</code> as follows:
|
||||
</p>
|
||||
<a id="je_dbt2"></a>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.je.DatabaseEntry;
|
||||
|
||||
...
|
||||
|
||||
// theKey and theData are DatabaseEntry objects. Database
|
||||
// retrieval is described later in this chapter. For now,
|
||||
// we assume some database get method has populated these
|
||||
// objects for us.
|
||||
|
||||
// Use DatabaseEntry.getData() to retrieve the encapsulated Java
|
||||
// byte array.
|
||||
|
||||
byte[] myKey = theKey.getData();
|
||||
byte[] myData = theData.getData();
|
||||
|
||||
String key = new String(myKey, "UTF-8");
|
||||
String data = new String(myData, "UTF-8"); </pre>
|
||||
<p>
|
||||
There are a large number of mechanisms that you can use to move data in
|
||||
and out of <code class="literal">byte</code> arrays. To help you with this
|
||||
activity, JE provides the bind APIs. These APIs allow you to
|
||||
efficiently store both primitive data types and complex objects in
|
||||
<code class="literal">byte</code> arrays.
|
||||
</p>
|
||||
<p>
|
||||
The next section describes basic database put and get operations. A
|
||||
basic understanding of database access is useful when describing database
|
||||
storage of more complex data such as is supported by the bind APIs. Basic
|
||||
bind API usage is then described in <a class="xref" href="bindAPI.html" title="Using the BIND APIs">Using the BIND APIs</a>.
|
||||
</p>
|
||||
<span>
|
||||
|
||||
</span>
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="dbUsage.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="baseapi.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="usingDbt.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Database Example </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Reading and Writing Database Records</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
122
docs/GettingStartedGuide/DeleteEntryWCursor.html
Normal file
122
docs/GettingStartedGuide/DeleteEntryWCursor.html
Normal file
|
|
@ -0,0 +1,122 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Deleting Records Using Cursors</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="Cursors.html" title="Chapter 9. Using Cursors" />
|
||||
<link rel="prev" href="PutEntryWCursor.html" title="Putting Records Using Cursors" />
|
||||
<link rel="next" href="ReplacingEntryWCursor.html" title="Replacing Records Using Cursors" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Deleting Records Using Cursors</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="PutEntryWCursor.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 9. Using Cursors</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="ReplacingEntryWCursor.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="DeleteEntryWCursor"></a>Deleting Records Using Cursors</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
|
||||
To delete a record using a cursor, simply position the cursor to the
|
||||
record that you want to delete and then call
|
||||
|
||||
<span>
|
||||
<code class="methodname">Cursor.delete()</code>.
|
||||
Note that after deleting a
|
||||
record, the value of <code class="methodname">Cursor.getCurrent()</code>
|
||||
is unchanged until such a
|
||||
time as the cursor is moved again. Also, if you call
|
||||
<code class="methodname">Cursor.delete()</code> two or more times in a row
|
||||
without repositioning the cursor, then all subsequent deletes result in
|
||||
a return value of <code class="literal">OperationStatus.KEYEMPTY</code>.
|
||||
</span>
|
||||
|
||||
|
||||
</p>
|
||||
<p>For example:</p>
|
||||
<a id="je_cursor8"></a>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.je.Cursor;
|
||||
import com.sleepycat.je.Database;
|
||||
import com.sleepycat.je.DatabaseEntry;
|
||||
import com.sleepycat.je.LockMode;
|
||||
import com.sleepycat.je.OperationStatus;
|
||||
|
||||
...
|
||||
|
||||
Cursor cursor = null;
|
||||
try {
|
||||
...
|
||||
// Database and environment open omitted for brevity
|
||||
...
|
||||
// Create DatabaseEntry objects
|
||||
// searchKey is some String.
|
||||
DatabaseEntry theKey = new DatabaseEntry(searchKey.getBytes("UTF-8"));
|
||||
DatabaseEntry theData = new DatabaseEntry();
|
||||
|
||||
// Open a cursor using a database handle
|
||||
cursor = myDatabase.openCursor(null, null);
|
||||
|
||||
// Position the cursor. Ignoring the return value for clarity
|
||||
OperationStatus retVal = cursor.getSearchKey(theKey, theData,
|
||||
LockMode.DEFAULT);
|
||||
|
||||
// Count the number of records using the given key. If there is only
|
||||
// one, delete that record.
|
||||
if (cursor.count() == 1) {
|
||||
System.out.println("Deleting " +
|
||||
new String(theKey.getData(), "UTF-8") +
|
||||
"|" +
|
||||
new String(theData.getData(), "UTF-8"));
|
||||
cursor.delete();
|
||||
}
|
||||
} catch (Exception e) {
|
||||
// Exception handling goes here
|
||||
} finally {
|
||||
// Make sure to close the cursor
|
||||
cursor.close();
|
||||
}</pre>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="PutEntryWCursor.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="Cursors.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="ReplacingEntryWCursor.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Putting Records Using Cursors </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Replacing Records Using Cursors</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
263
docs/GettingStartedGuide/EnvProps.html
Normal file
263
docs/GettingStartedGuide/EnvProps.html
Normal file
|
|
@ -0,0 +1,263 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Environment Properties</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="env.html" title="Chapter 2. Database Environments" />
|
||||
<link rel="prev" href="envclose.html" title="Closing Database Environments" />
|
||||
<link rel="next" href="envStats.html" title="Environment Statistics" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Environment Properties</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="envclose.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 2. Database Environments</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="envStats.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="EnvProps"></a>Environment Properties</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="toc">
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="EnvProps.html#envconfig">The EnvironmentConfig Class</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="EnvProps.html#envhandleconfig">EnvironmentMutableConfig</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</div>
|
||||
<p>
|
||||
You set properties for the <code class="classname">Environment</code> using the
|
||||
<code class="classname">EnvironmentConfig</code> class. You can also set properties for a
|
||||
specific <code class="classname">Environment</code> instance using
|
||||
<code class="classname">EnvironmentMutableConfig</code>.
|
||||
</p>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="envconfig"></a>The EnvironmentConfig Class</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
The <code class="classname">EnvironmentConfig</code> class makes a large number of fields and
|
||||
methods available to you. Describing all of these tuning parameters is beyond the scope of
|
||||
this manual. However, there are a few properties that you are likely to want to set. They
|
||||
are described here.
|
||||
</p>
|
||||
<p>
|
||||
Note that for each of the properties that you can commonly set, there is a corresponding
|
||||
getter method. Also, you can always retrieve the
|
||||
<code class="classname">EnvironmentConfig</code> object used by your environment using the
|
||||
<code class="methodname">Environment.getConfig()</code> method.
|
||||
</p>
|
||||
<p>
|
||||
You set environment configuration parameters using the following methods on the
|
||||
<code class="classname">EnvironmentConfig</code> class:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
<code class="methodname">EnvironmentConfig.setAllowCreate()</code>
|
||||
</p>
|
||||
<p>
|
||||
If <code class="literal">true</code>, the database environment is created when it is opened.
|
||||
If <code class="literal">false</code>, environment open fails if the environment does not
|
||||
exist. This property has no meaning if the database environment already exists.
|
||||
Default is <code class="literal">false</code>.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="methodname">EnvironmentConfig.setReadOnly()</code>
|
||||
</p>
|
||||
<p>If <code class="literal">true</code>, then all databases opened in this
|
||||
environment must be opened as read-only. If you are writing a
|
||||
multi-process application, then all but one of your processes must set
|
||||
this value to <code class="literal">true</code>. Default is <code class="literal">false</code>.</p>
|
||||
<p>
|
||||
You can also set this property using the <code class="literal">je.env.isReadOnly</code>
|
||||
parameter in your <code class="filename"><span class="emphasis"><em>env_home</em></span>/je.properties</code> file.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="methodname">EnvironmentConfig.setTransactional()</code>
|
||||
</p>
|
||||
<p>If <code class="literal">true</code>, configures the database environment
|
||||
to support transactions. Default is <code class="literal">false</code>.</p>
|
||||
<p>
|
||||
You can also set this property using the <code class="literal">je.env.isTransactional</code>
|
||||
parameter in your <code class="filename"><span class="emphasis"><em>env_home</em></span>/je.properties</code> file.
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<p>For example:</p>
|
||||
<a id="je_env3"></a>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.je.DatabaseException;
|
||||
import com.sleepycat.je.Environment;
|
||||
import com.sleepycat.je.EnvironmentConfig;
|
||||
|
||||
import java.io.File;
|
||||
|
||||
...
|
||||
|
||||
Environment myDatabaseEnvironment = null;
|
||||
try {
|
||||
EnvironmentConfig envConfig = new EnvironmentConfig();
|
||||
envConfig.setAllowCreate(true);
|
||||
envConfig.setTransactional(true);
|
||||
myDatabaseEnvironment =
|
||||
new Environment(new File("/export/dbEnv"), envConfig);
|
||||
} catch (DatabaseException dbe) {
|
||||
System.err.println(dbe.toString());
|
||||
System.exit(1);
|
||||
} </pre>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="envhandleconfig"></a>EnvironmentMutableConfig</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
<code class="classname">EnvironmentMutableConfig</code> manages properties that can be reset after the
|
||||
<code class="classname">Environment</code> object has been constructed. In addition, <code class="classname">EnvironmentConfig</code>
|
||||
extends <code class="classname">EnvironmentMutableConfig</code>, so you can set these mutable properties at
|
||||
<code class="classname">Environment</code> construction time if necessary.
|
||||
</p>
|
||||
<p>
|
||||
The <code class="classname">EnvironmentMutableConfig</code> class allows you to set the following
|
||||
properties:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
<code class="literal">setCachePercent()</code>
|
||||
</p>
|
||||
<p>
|
||||
Determines the percentage of JVM memory available to the JE cache.
|
||||
See
|
||||
|
||||
<a class="xref" href="cachesize.html" title="Sizing the Cache">Sizing the Cache</a>
|
||||
for more information.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="literal">setCacheSize()</code>
|
||||
</p>
|
||||
<p>
|
||||
Determines the total amount of memory available to the database cache.
|
||||
See <a class="xref" href="cachesize.html" title="Sizing the Cache">Sizing the Cache</a>
|
||||
for more information.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="literal">setTxnNoSync()</code>
|
||||
</p>
|
||||
<p>
|
||||
Determines whether change records created due to a transaction commit are written to the backing
|
||||
log files on disk. A value of <code class="literal">true</code> causes
|
||||
the data to not be flushed to
|
||||
disk. See the <em class="citetitle">Berkeley DB, Java Edition Getting Started with Transaction Processing</em> guide.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="literal">setTxnWriteNoSync()</code>
|
||||
</p>
|
||||
<p>
|
||||
Determines whether logs are flushed on transaction commit (the logs are still written, however).
|
||||
By setting this value to <code class="literal">true</code>, you potentially gain better performance than if
|
||||
you flush the logs on commit, but you do so by losing some of your transaction durability guarantees.
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<p>
|
||||
There is also a corresponding getter method (<code class="methodname">getTxnNoSync()</code>).
|
||||
Moreover, you can always retrieve your environment's
|
||||
<code class="classname">EnvironmentMutableConfig</code> object by
|
||||
using the <code class="methodname">Environment.getMutableConfig()</code> method.
|
||||
</p>
|
||||
<p>
|
||||
For example:
|
||||
</p>
|
||||
<a id="je_env4"></a>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.je.DatabaseException;
|
||||
import com.sleepycat.je.Environment;
|
||||
import com.sleepycat.je.EnvironmentMutableConfig;
|
||||
|
||||
import java.io.File;
|
||||
|
||||
|
||||
...
|
||||
|
||||
try {
|
||||
Environment myEnv = new Environment(new File("/export/dbEnv"), null);
|
||||
EnvironmentMutableConfig envMutableConfig =
|
||||
new EnvironmentMutableConfig();
|
||||
envMutableConfig.setTxnNoSync(true);
|
||||
myEnv.setMutableConfig(envMutableConfig);
|
||||
} catch (DatabaseException dbe) {
|
||||
// Exception handling goes here
|
||||
} </pre>
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="envclose.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="env.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="envStats.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Closing Database Environments </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Environment Statistics</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
691
docs/GettingStartedGuide/Positioning.html
Normal file
691
docs/GettingStartedGuide/Positioning.html
Normal file
|
|
@ -0,0 +1,691 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Getting Records Using the Cursor</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="Cursors.html" title="Chapter 9. Using Cursors" />
|
||||
<link rel="prev" href="Cursors.html" title="Chapter 9. Using Cursors" />
|
||||
<link rel="next" href="PutEntryWCursor.html" title="Putting Records Using Cursors" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Getting Records Using the Cursor</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="Cursors.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 9. Using Cursors</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="PutEntryWCursor.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="Positioning"></a>Getting Records Using the Cursor</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="toc">
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="Positioning.html#diskorderedcursors">Disk Ordered Cursors</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="Positioning.html#cursorsearch">Searching for Records</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="Positioning.html#getdups">Working with Duplicate Records</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</div>
|
||||
<p>
|
||||
To iterate over database records, from the first record to
|
||||
the last, simply open the cursor and then use the
|
||||
<code class="methodname">Cursor.getNext()</code>
|
||||
|
||||
|
||||
method.
|
||||
|
||||
For example:
|
||||
</p>
|
||||
<a id="je_cursor3"></a>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.je.Cursor;
|
||||
import com.sleepycat.je.Database;
|
||||
import com.sleepycat.je.DatabaseEntry;
|
||||
import com.sleepycat.je.DatabaseException;
|
||||
import com.sleepycat.je.LockMode;
|
||||
import com.sleepycat.je.OperationStatus;
|
||||
|
||||
...
|
||||
|
||||
Cursor cursor = null;
|
||||
try {
|
||||
...
|
||||
// Database and environment open omitted for brevity
|
||||
...
|
||||
|
||||
// Open the cursor.
|
||||
cursor = myDatabase.openCursor(null, null);
|
||||
|
||||
// Cursors need a pair of DatabaseEntry objects to operate. These hold
|
||||
// the key and data found at any given position in the database.
|
||||
DatabaseEntry foundKey = new DatabaseEntry();
|
||||
DatabaseEntry foundData = new DatabaseEntry();
|
||||
|
||||
// To iterate, just call getNext() until the last database record has
|
||||
// been read. All cursor operations return an OperationStatus, so just
|
||||
// read until we no longer see OperationStatus.SUCCESS
|
||||
while (cursor.getNext(foundKey, foundData, LockMode.DEFAULT) ==
|
||||
OperationStatus.SUCCESS) {
|
||||
// getData() on the DatabaseEntry objects returns the byte array
|
||||
// held by that object. We use this to get a String value. If the
|
||||
// DatabaseEntry held a byte array representation of some other
|
||||
// data type (such as a complex object) then this operation would
|
||||
// look considerably different.
|
||||
String keyString = new String(foundKey.getData(), "UTF-8");
|
||||
String dataString = new String(foundData.getData(), "UTF-8");
|
||||
System.out.println("Key | Data : " + keyString + " | " +
|
||||
dataString + "");
|
||||
}
|
||||
} catch (DatabaseException de) {
|
||||
System.err.println("Error accessing database." + de);
|
||||
} finally {
|
||||
// Cursors must be closed.
|
||||
cursor.close();
|
||||
}</pre>
|
||||
<p>
|
||||
To iterate over the database from the last record to the first,
|
||||
instantiate the cursor, and then
|
||||
use <code class="methodname">Cursor.getPrev()</code> until you read the first record in
|
||||
the database. For example:
|
||||
</p>
|
||||
<a id="je_cursor4"></a>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.je.Cursor;
|
||||
import com.sleepycat.je.Database;
|
||||
import com.sleepycat.je.DatabaseEntry;
|
||||
import com.sleepycat.je.DatabaseException;
|
||||
import com.sleepycat.je.LockMode;
|
||||
import com.sleepycat.je.OperationStatus;
|
||||
|
||||
...
|
||||
|
||||
Cursor cursor = null;
|
||||
try {
|
||||
...
|
||||
// Database and environment open omitted for brevity
|
||||
...
|
||||
|
||||
// Open the cursor.
|
||||
cursor = myDatabase.openCursor(null, null);
|
||||
|
||||
// Get the DatabaseEntry objects that the cursor will use.
|
||||
DatabaseEntry foundKey = new DatabaseEntry();
|
||||
DatabaseEntry foundData = new DatabaseEntry();
|
||||
|
||||
// Iterate from the last record to the first in the database
|
||||
while (cursor.getPrev(foundKey, foundData, LockMode.DEFAULT) ==
|
||||
OperationStatus.SUCCESS) {
|
||||
|
||||
String theKey = new String(foundKey.getData(), "UTF-8");
|
||||
String theData = new String(foundData.getData(), "UTF-8");
|
||||
System.out.println("Key | Data : " + theKey + " | " +
|
||||
theData + "");
|
||||
}
|
||||
} catch (DatabaseException de) {
|
||||
System.err.println("Error accessing database." + de);
|
||||
} finally {
|
||||
// Cursors must be closed.
|
||||
cursor.close();
|
||||
}</pre>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="diskorderedcursors"></a>Disk Ordered Cursors</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
The previous example shows how to scan through the records in
|
||||
your database sequentially; that is, in the record's sort order.
|
||||
This is mostly determined by the value contained in the records' keys
|
||||
(additional sorting is required in the case of duplicate
|
||||
records). However, you can use cursors to retrieve records based
|
||||
on how they are stored on disk. This can improve retrieval times,
|
||||
and is useful if your application needs to scan all the records
|
||||
in the database quickly, without concern for key sort order.
|
||||
You do this using the <code class="classname">DiskOrderedCursor</code>
|
||||
class.
|
||||
</p>
|
||||
<p>
|
||||
<code class="classname">DiskOrderedClass</code> works in the same way as
|
||||
a regular cusor: you simply open the cursor, then retrieve
|
||||
records one after another using the
|
||||
<code class="methodname">DiskOrderedClass.getNext()</code>
|
||||
method.
|
||||
</p>
|
||||
<p>
|
||||
You open a <code class="classname">DiskOrderedCursor</code>
|
||||
using the <code class="methodname">Database.openCursor()</code>
|
||||
method. This version of the method takes a single parameter: an
|
||||
instance of the
|
||||
<code class="classname">DiskOrderedCursorConfig</code>
|
||||
class, which can be used to configure various aspects of the
|
||||
<code class="classname">DiskOrderedCursor</code>
|
||||
class.
|
||||
</p>
|
||||
<a id="je_diskorderedcursor1"></a>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.je.Database;
|
||||
import com.sleepycat.je.DatabaseEntry;
|
||||
import com.sleepycat.je.DatabaseException;
|
||||
import com.sleepycat.je.DiskOrderedCursor;
|
||||
import com.sleepycat.je.DiskOrderedCursorConfig;
|
||||
import com.sleepycat.je.LockMode;
|
||||
import com.sleepycat.je.OperationStatus;
|
||||
|
||||
...
|
||||
|
||||
DiskOrderedCursor dcursor = null;
|
||||
DiskOrderedCursorConfig docc = new DiskOrderedCursorConfig();
|
||||
try {
|
||||
...
|
||||
// Database and environment open omitted for brevity
|
||||
...
|
||||
|
||||
// Open the cursor.
|
||||
dcursor = myDatabase.openCursor(docc);
|
||||
|
||||
// Cursors need a pair of DatabaseEntry objects to operate. These hold
|
||||
// the key and data found at any given position in the database.
|
||||
DatabaseEntry foundKey = new DatabaseEntry();
|
||||
DatabaseEntry foundData = new DatabaseEntry();
|
||||
|
||||
// To iterate, just call getNext() until the last database record has
|
||||
// been read. All cursor operations return an OperationStatus, so just
|
||||
// read until we no longer see OperationStatus.SUCCESS
|
||||
while (dcursor.getNext(foundKey, foundData, LockMode.DEFAULT) ==
|
||||
OperationStatus.SUCCESS) {
|
||||
// getData() on the DatabaseEntry objects returns the byte array
|
||||
// held by that object. We use this to get a String value. If the
|
||||
// DatabaseEntry held a byte array representation of some other
|
||||
// data type (such as a complex object) then this operation would
|
||||
// look considerably different.
|
||||
String keyString = new String(foundKey.getData(), "UTF-8");
|
||||
String dataString = new String(foundData.getData(), "UTF-8");
|
||||
System.out.println("Key | Data : " + keyString + " | " +
|
||||
dataString + "");
|
||||
}
|
||||
} catch (DatabaseException de) {
|
||||
System.err.println("Error accessing database." + de);
|
||||
} finally {
|
||||
// Cursors must be closed.
|
||||
cursor.close();
|
||||
}</pre>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="cursorsearch"></a>Searching for Records</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
You can use cursors to search for database records. You can search based
|
||||
on just a key, or you can search based on both the key and the data.
|
||||
You can also perform partial matches if your database supports sorted
|
||||
duplicate sets. In all cases, the key and data parameters of these
|
||||
methods are filled with the key and data values of the database record
|
||||
to which the cursor is positioned as a result of the search.
|
||||
</p>
|
||||
<p>
|
||||
Also, if the search fails, then cursor's state is left unchanged
|
||||
and
|
||||
<code class="literal">OperationStatus.NOTFOUND</code>
|
||||
|
||||
is returned.
|
||||
|
||||
|
||||
</p>
|
||||
<p>
|
||||
The following <code class="classname">Cursor</code> methods allow you to
|
||||
perform database searches:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
<code class="methodname">Cursor.getSearchKey()</code>
|
||||
|
||||
</p>
|
||||
<p>
|
||||
Moves the cursor to the first record in the database with
|
||||
the specified key.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="methodname">Cursor.getSearchKeyRange()</code>
|
||||
|
||||
</p>
|
||||
<p>
|
||||
|
||||
<span>Moves the cursor</span>
|
||||
|
||||
to the first record in the database whose
|
||||
key is greater than or equal to the specified key. This comparison
|
||||
is determined by the
|
||||
<span>comparator</span>
|
||||
|
||||
that you provide for the database. If no
|
||||
<span>comparator</span>
|
||||
|
||||
is provided, then the default
|
||||
<span> unsigned byte-by-byte </span>
|
||||
lexicographical sorting is used.
|
||||
</p>
|
||||
<p>
|
||||
For example, suppose you have database records that use the
|
||||
following
|
||||
<span>Strings</span>
|
||||
|
||||
as keys:
|
||||
</p>
|
||||
<pre class="programlisting">Alabama
|
||||
Alaska
|
||||
Arizona</pre>
|
||||
<p>
|
||||
Then providing a search key of <code class="literal">Alaska</code> moves the
|
||||
cursor to the second key noted above. Providing a key of
|
||||
<code class="literal">Al</code> moves the cursor to the first key (<code class="literal">Alabama</code>), providing
|
||||
a search key of <code class="literal">Alas</code> moves the cursor to the second key
|
||||
(<code class="literal">Alaska</code>), and providing a key of <code class="literal">Ar</code> moves the
|
||||
cursor to the last key (<code class="literal">Arizona</code>).
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="methodname">Cursor.getSearchBoth()</code>
|
||||
|
||||
</p>
|
||||
<p>
|
||||
Moves the cursor to the first record in the database that uses
|
||||
the specified key and data.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="methodname">Cursor.getSearchBothRange()</code>
|
||||
|
||||
</p>
|
||||
<p>
|
||||
Moves the cursor to the first record in the database whose key matches the specified
|
||||
key and whose data is
|
||||
greater than or equal to the specified data. If the database supports
|
||||
duplicate records, then on matching the key, the cursor is moved to
|
||||
the duplicate record with the smallest data that is greater than or
|
||||
equal to the specified data.
|
||||
</p>
|
||||
<p>
|
||||
For example,
|
||||
<span>suppose you have</span>
|
||||
|
||||
database records that use the following key/data pairs:
|
||||
</p>
|
||||
<pre class="programlisting">Alabama/Athens
|
||||
Alabama/Florence
|
||||
Alaska/Anchorage
|
||||
Alaska/Fairbanks
|
||||
Arizona/Avondale
|
||||
Arizona/Florence </pre>
|
||||
<p>then providing:</p>
|
||||
<div class="informaltable">
|
||||
<table border="1" width="80%">
|
||||
<colgroup>
|
||||
<col />
|
||||
<col />
|
||||
<col />
|
||||
</colgroup>
|
||||
<thead>
|
||||
<tr>
|
||||
<th>a search key of ...</th>
|
||||
<th>and a search data of ...</th>
|
||||
<th>moves the cursor to ...</th>
|
||||
</tr>
|
||||
</thead>
|
||||
<tbody>
|
||||
<tr>
|
||||
<td>Alaska</td>
|
||||
<td>Fa</td>
|
||||
<td>Alaska/Fairbanks</td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td>Arizona</td>
|
||||
<td>Fl</td>
|
||||
<td>Arizona/Florence</td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td>Alaska</td>
|
||||
<td>An</td>
|
||||
<td>Alaska/Anchorage</td>
|
||||
</tr>
|
||||
</tbody>
|
||||
</table>
|
||||
</div>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<p>
|
||||
For example, assuming a database containing sorted duplicate records of
|
||||
U.S. States/U.S Cities key/data pairs (both as
|
||||
<span>Strings),</span>
|
||||
|
||||
then the following code fragment can be used to position the cursor
|
||||
to any record in the database and print its key/data values:
|
||||
<span>
|
||||
|
||||
</span>
|
||||
</p>
|
||||
<a id="je_cursor5"></a>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.je.Cursor;
|
||||
import com.sleepycat.je.Database;
|
||||
import com.sleepycat.je.DatabaseEntry;
|
||||
import com.sleepycat.je.DatabaseException;
|
||||
import com.sleepycat.je.LockMode;
|
||||
import com.sleepycat.je.OperationStatus;
|
||||
|
||||
...
|
||||
|
||||
// For this example, hard code the search key and data
|
||||
String searchKey = "Alaska";
|
||||
String searchData = "Fa";
|
||||
|
||||
Cursor cursor = null;
|
||||
try {
|
||||
...
|
||||
// Database and environment open omitted for brevity
|
||||
...
|
||||
|
||||
// Open the cursor.
|
||||
cursor = myDatabase.openCursor(null, null);
|
||||
|
||||
DatabaseEntry theKey =
|
||||
new DatabaseEntry(searchKey.getBytes("UTF-8"));
|
||||
DatabaseEntry theData =
|
||||
new DatabaseEntry(searchData.getBytes("UTF-8"));
|
||||
|
||||
// Open a cursor using a database handle
|
||||
cursor = myDatabase.openCursor(null, null);
|
||||
|
||||
// Perform the search
|
||||
OperationStatus retVal = cursor.getSearchBothRange(theKey, theData,
|
||||
LockMode.DEFAULT);
|
||||
// NOTFOUND is returned if a record cannot be found whose key
|
||||
// matches the search key AND whose data begins with the search data.
|
||||
if (retVal == OperationStatus.NOTFOUND) {
|
||||
System.out.println(searchKey + "/" + searchData +
|
||||
" not matched in database " +
|
||||
myDatabase.getDatabaseName());
|
||||
} else {
|
||||
// Upon completing a search, the key and data DatabaseEntry
|
||||
// parameters for getSearchBothRange() are populated with the
|
||||
// key/data values of the found record.
|
||||
String foundKey = new String(theKey.getData(), "UTF-8");
|
||||
String foundData = new String(theData.getData(), "UTF-8");
|
||||
System.out.println("Found record " + foundKey + "/" + foundData +
|
||||
"for search key/data: " + searchKey +
|
||||
"/" + searchData);
|
||||
}
|
||||
|
||||
} catch (Exception e) {
|
||||
// Exception handling goes here
|
||||
} finally {
|
||||
// Make sure to close the cursor
|
||||
cursor.close();
|
||||
}</pre>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="getdups"></a>Working with Duplicate Records</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
If your database supports duplicate records, then it can potentially
|
||||
contain multiple records that share the same key.
|
||||
|
||||
<span>
|
||||
Using normal database get operations, you can only ever obtain the
|
||||
first such record in a set of duplicate records. To access subsequent
|
||||
duplicates, use a cursor.
|
||||
</span>
|
||||
|
||||
|
||||
|
||||
The following
|
||||
<span><code class="methodname">Cursor</code> methods</span>
|
||||
|
||||
|
||||
are interesting when working with databases that support duplicate records:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
<span>
|
||||
<code class="methodname">Cursor.getNext()</code>,
|
||||
<code class="methodname">Cursor.getPrev()</code>
|
||||
</span>
|
||||
|
||||
</p>
|
||||
<p>
|
||||
Shows the next/previous record in the database, regardless of
|
||||
whether it is a duplicate of the current record. For an example of
|
||||
using these methods, see <a class="xref" href="Positioning.html" title="Getting Records Using the Cursor">Getting Records Using the Cursor</a>.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="methodname">Cursor.getSearchBothRange()</code>
|
||||
|
||||
</p>
|
||||
<p>
|
||||
Useful for seeking the cursor to a specific record, regardless of
|
||||
whether it is a duplicate record. See <a class="xref" href="Positioning.html#cursorsearch" title="Searching for Records">Searching for Records</a> for more
|
||||
information.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<span>
|
||||
<code class="methodname">Cursor.getNextNoDup()</code>,
|
||||
<code class="methodname">Cursor.getPrevNoDup()</code>
|
||||
</span>
|
||||
|
||||
</p>
|
||||
<p>
|
||||
Gets the next/previous non-duplicate record in the database. This
|
||||
allows you to skip over all the duplicates in a set of duplicate
|
||||
records. If you call
|
||||
<span><code class="methodname">Cursor.getPrevNoDup()</code>,</span>
|
||||
|
||||
then the cursor is positioned to the last record for the previous
|
||||
key in the database. For example, if you have the following records
|
||||
in your database:
|
||||
</p>
|
||||
<pre class="programlisting">Alabama/Athens
|
||||
Alabama/Florence
|
||||
Alaska/Anchorage
|
||||
Alaska/Fairbanks
|
||||
Arizona/Avondale
|
||||
Arizona/Florence</pre>
|
||||
<p>
|
||||
and your cursor is positioned to <code class="literal">Alaska/Fairbanks</code>,
|
||||
and you then call
|
||||
<span><code class="methodname">Cursor.getPrevNoDup()</code>,</span>
|
||||
|
||||
then the cursor is positioned to Alabama/Florence. Similarly, if
|
||||
you call
|
||||
<span><code class="methodname">Cursor.getNextNoDup()</code>,</span>
|
||||
|
||||
|
||||
then the cursor is positioned to the first record corresponding to
|
||||
the next key in the database.
|
||||
</p>
|
||||
<p>
|
||||
If there is no next/previous key in the database, then
|
||||
<code class="literal">OperationStatus.NOTFOUND</code>
|
||||
|
||||
is returned, and the cursor is left unchanged.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<span>
|
||||
<code class="methodname">Cursor.getNextDup()</code>,
|
||||
<code class="methodname">Cursor.getPrevDup()</code>
|
||||
</span>
|
||||
|
||||
</p>
|
||||
<p>
|
||||
|
||||
Gets the
|
||||
<span>next/previous</span>
|
||||
|
||||
record that shares the current key. If the
|
||||
cursor is positioned at the last record in the duplicate set and
|
||||
you call
|
||||
<span><code class="methodname">Cursor.getNextDup()</code>,</span>
|
||||
|
||||
|
||||
then
|
||||
<code class="literal">OperationStatus.NOTFOUND</code>
|
||||
|
||||
is returned and the cursor is left unchanged.
|
||||
<span>
|
||||
Likewise, if you call
|
||||
<code class="methodname">getPrevDup()</code> and the
|
||||
cursor is positioned at the first record in the duplicate set, then
|
||||
<code class="literal">OperationStatus.NOTFOUND</code> is returned and the
|
||||
cursor is left unchanged.
|
||||
</span>
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="methodname">Cursor.count()</code>
|
||||
</p>
|
||||
<p>Returns the total number of records that share the current key.</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<p>
|
||||
For example, the following code fragment positions a cursor to a key
|
||||
|
||||
<span>and, if the key contains duplicate records,
|
||||
displays all the duplicates.</span>
|
||||
|
||||
|
||||
|
||||
<span>Note that the following code fragment assumes that the database contains
|
||||
only String objects for the keys and data.</span>
|
||||
</p>
|
||||
<a id="je_cursor6"></a>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.je.Cursor;
|
||||
import com.sleepycat.je.Database;
|
||||
import com.sleepycat.je.DatabaseEntry;
|
||||
import com.sleepycat.je.DatabaseException;
|
||||
import com.sleepycat.je.LockMode;
|
||||
import com.sleepycat.je.OperationStatus;
|
||||
|
||||
...
|
||||
|
||||
Cursor cursor = null;
|
||||
try {
|
||||
...
|
||||
// Database and environment open omitted for brevity
|
||||
...
|
||||
|
||||
// Create DatabaseEntry objects
|
||||
// searchKey is some String.
|
||||
DatabaseEntry theKey = new DatabaseEntry(searchKey.getBytes("UTF-8"));
|
||||
DatabaseEntry theData = new DatabaseEntry();
|
||||
|
||||
// Open a cursor using a database handle
|
||||
cursor = myDatabase.openCursor(null, null);
|
||||
|
||||
// Position the cursor
|
||||
// Ignoring the return value for clarity
|
||||
OperationStatus retVal = cursor.getSearchKey(theKey, theData,
|
||||
LockMode.DEFAULT);
|
||||
|
||||
// Count the number of duplicates. If the count is greater than 1,
|
||||
// print the duplicates.
|
||||
if (cursor.count() > 1) {
|
||||
while (retVal == OperationStatus.SUCCESS) {
|
||||
String keyString = new String(theKey.getData(), "UTF-8");
|
||||
String dataString = new String(theData.getData(), "UTF-8");
|
||||
System.out.println("Key | Data : " + keyString + " | " +
|
||||
dataString + "");
|
||||
|
||||
retVal = cursor.getNextDup(theKey, theData, LockMode.DEFAULT);
|
||||
}
|
||||
}
|
||||
} catch (Exception e) {
|
||||
// Exception handling goes here
|
||||
} finally {
|
||||
// Make sure to close the cursor
|
||||
cursor.close();
|
||||
}</pre>
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="Cursors.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="Cursors.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="PutEntryWCursor.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Chapter 9. Using Cursors </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Putting Records Using Cursors</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
186
docs/GettingStartedGuide/PutEntryWCursor.html
Normal file
186
docs/GettingStartedGuide/PutEntryWCursor.html
Normal file
|
|
@ -0,0 +1,186 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Putting Records Using Cursors</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="Cursors.html" title="Chapter 9. Using Cursors" />
|
||||
<link rel="prev" href="Positioning.html" title="Getting Records Using the Cursor" />
|
||||
<link rel="next" href="DeleteEntryWCursor.html" title="Deleting Records Using Cursors" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Putting Records Using Cursors</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="Positioning.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 9. Using Cursors</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="DeleteEntryWCursor.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="PutEntryWCursor"></a>Putting Records Using Cursors</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
You can use cursors to put records into the database. JE's behavior
|
||||
when putting records into the database differs depending on whether the
|
||||
database supports duplicate records. If duplicates are allowed, its
|
||||
behavior also differs depending on whether a comparator is provided for
|
||||
the database. (Comparators are described in
|
||||
<a class="xref" href="comparator.html" title="Using Comparators">Using Comparators</a>).
|
||||
</p>
|
||||
<p>
|
||||
Note that when putting records to the database using a cursor, the
|
||||
cursor is positioned at the record you inserted.
|
||||
</p>
|
||||
<p>
|
||||
You can use the following methods to put records to the database:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
<code class="methodname">Cursor.put()</code>
|
||||
</p>
|
||||
<p>
|
||||
If the provided key does not exist in the database,
|
||||
then the order that the record is put into the database
|
||||
is determined by the BTree (key) comparator in use by the database.
|
||||
</p>
|
||||
<p>
|
||||
If the provided key already exists in the database, and the database
|
||||
does not support sorted duplicates, then the existing record data is
|
||||
replaced with the data provided on this method.
|
||||
</p>
|
||||
<p>
|
||||
If the provided key already exists in the database, and the database
|
||||
does support sorted duplicates, then the order that the record is
|
||||
inserted into the database is determined by the duplicate comparator
|
||||
in use by the database.
|
||||
</p>
|
||||
<p>
|
||||
Note that a version of this method exists which allows you to
|
||||
specify a Time to Live value for the record that you are
|
||||
inserting. See <a class="xref" href="timetolive.html" title="Using Time to Live">Using Time to Live</a>
|
||||
for more information.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="methodname">Cursor.putNoDupData()</code>
|
||||
|
||||
</p>
|
||||
<p>
|
||||
If the provided key <span>and data</span> already exists
|
||||
in the database, then this method returns
|
||||
<code class="literal">OperationStatus.KEYEXIST</code>.
|
||||
</p>
|
||||
<p>
|
||||
If the key does not exist, then the order that the record is put into the database
|
||||
is determined by the
|
||||
<span>
|
||||
BTree (key) comparator in use by the database.
|
||||
</span>
|
||||
|
||||
</p>
|
||||
<span></span>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="methodname">Cursor.putNoOverwrite()</code>
|
||||
</p>
|
||||
<p>
|
||||
If the provided key already exists
|
||||
in the database, then this method returns
|
||||
<code class="literal">OperationStatus.KEYEXIST</code>.
|
||||
</p>
|
||||
<p>
|
||||
If the key does not exist, then the order that the record is put into the database
|
||||
is determined by the BTree (key) comparator in use by the database.
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<p>For example:</p>
|
||||
<a id="je_cursor7"></a>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.je.Cursor;
|
||||
import com.sleepycat.je.Database;
|
||||
import com.sleepycat.je.DatabaseEntry;
|
||||
import com.sleepycat.je.OperationStatus;
|
||||
|
||||
...
|
||||
|
||||
// Create the data to put into the database
|
||||
String key1str = "My first string";
|
||||
String data1str = "My first data";
|
||||
String key2str = "My second string";
|
||||
String data2str = "My second data";
|
||||
String data3str = "My third data";
|
||||
|
||||
Cursor cursor = null;
|
||||
try {
|
||||
...
|
||||
// Database and environment open omitted for brevity
|
||||
...
|
||||
|
||||
DatabaseEntry key1 = new DatabaseEntry(key1str.getBytes("UTF-8"));
|
||||
DatabaseEntry data1 = new DatabaseEntry(data1str.getBytes("UTF-8"));
|
||||
DatabaseEntry key2 = new DatabaseEntry(key2str.getBytes("UTF-8"));
|
||||
DatabaseEntry data2 = new DatabaseEntry(data2str.getBytes("UTF-8"));
|
||||
DatabaseEntry data3 = new DatabaseEntry(data3str.getBytes("UTF-8"));
|
||||
|
||||
// Open a cursor using a database handle
|
||||
cursor = myDatabase.openCursor(null, null);
|
||||
|
||||
// Assuming an empty database.
|
||||
|
||||
OperationStatus retVal = cursor.put(key1, data1); // SUCCESS
|
||||
retVal = cursor.put(key2, data2); // SUCCESS
|
||||
retVal = cursor.put(key2, data3); // SUCCESS if dups allowed,
|
||||
// KEYEXIST if not.
|
||||
|
||||
} catch (Exception e) {
|
||||
// Exception handling goes here
|
||||
} finally {
|
||||
// Make sure to close the cursor
|
||||
cursor.close();
|
||||
}</pre>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="Positioning.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="Cursors.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="DeleteEntryWCursor.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Getting Records Using the Cursor </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Deleting Records Using Cursors</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
123
docs/GettingStartedGuide/ReplacingEntryWCursor.html
Normal file
123
docs/GettingStartedGuide/ReplacingEntryWCursor.html
Normal file
|
|
@ -0,0 +1,123 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Replacing Records Using Cursors</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="Cursors.html" title="Chapter 9. Using Cursors" />
|
||||
<link rel="prev" href="DeleteEntryWCursor.html" title="Deleting Records Using Cursors" />
|
||||
<link rel="next" href="cursorUsage.html" title="Cursor Example" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Replacing Records Using Cursors</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="DeleteEntryWCursor.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 9. Using Cursors</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="cursorUsage.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="ReplacingEntryWCursor"></a>Replacing Records Using Cursors</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
You replace the data for a database record by using
|
||||
<span>
|
||||
<code class="methodname">Cursor.putCurrent()</code>.
|
||||
This method takes just one
|
||||
argument — the data that you want to write to the current location in the
|
||||
database.
|
||||
</span>
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
</p>
|
||||
<a id="je_cursor9"></a>
|
||||
<pre class="programlisting">import com.sleepycat.je.Cursor;
|
||||
|
||||
import com.sleepycat.je.Database;
|
||||
import com.sleepycat.je.DatabaseEntry;
|
||||
import com.sleepycat.je.LockMode;
|
||||
import com.sleepycat.je.OperationStatus;
|
||||
|
||||
...
|
||||
Cursor cursor = null;
|
||||
try {
|
||||
...
|
||||
// Database and environment open omitted for brevity
|
||||
...
|
||||
// Create DatabaseEntry objects
|
||||
// searchKey is some String.
|
||||
DatabaseEntry theKey = new DatabaseEntry(searchKey.getBytes("UTF-8"));
|
||||
DatabaseEntry theData = new DatabaseEntry();
|
||||
|
||||
// Open a cursor using a database handle
|
||||
cursor = myDatabase.openCursor(null, null);
|
||||
|
||||
// Position the cursor. Ignoring the return value for clarity
|
||||
OperationStatus retVal = cursor.getSearchKey(theKey, theData,
|
||||
LockMode.DEFAULT);
|
||||
|
||||
// Replacement data
|
||||
String replaceStr = "My replacement string";
|
||||
DatabaseEntry replacementData =
|
||||
new DatabaseEntry(replaceStr.getBytes("UTF-8"));
|
||||
cursor.putCurrent(replacementData);
|
||||
} catch (Exception e) {
|
||||
// Exception handling goes here
|
||||
} finally {
|
||||
// Make sure to close the cursor
|
||||
cursor.close();
|
||||
}</pre>
|
||||
<p>
|
||||
Note that this method cannot be used if the record that you are trying
|
||||
to replace is a member of a duplicate set. This is because records must
|
||||
be sorted by their data and replacement would violate that sort order.
|
||||
</p>
|
||||
<p>
|
||||
|
||||
<span>If</span>
|
||||
you want to replace the data contained by a duplicate record,
|
||||
|
||||
delete the record and create a new record with the desired key and data.
|
||||
</p>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="DeleteEntryWCursor.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="Cursors.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="cursorUsage.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Deleting Records Using Cursors </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Cursor Example</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
237
docs/GettingStartedGuide/admin.html
Normal file
237
docs/GettingStartedGuide/admin.html
Normal file
|
|
@ -0,0 +1,237 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Part III. Administering JE Applications</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="prev" href="indexusage.html" title="Secondary Database Example" />
|
||||
<link rel="next" href="backuprestore.html" title="Chapter 11. Backing up and Restoring Berkeley DB Java Edition Applications" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Part III. Administering JE Applications</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="indexusage.html">Prev</a> </td>
|
||||
<th width="60%" align="center"> </th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="backuprestore.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="part" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h1 class="title"><a id="admin"></a>Part III. Administering JE Applications</h1>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="partintro" lang="en" xml:lang="en">
|
||||
<div></div>
|
||||
<p>
|
||||
This section discusses concepts and mechanisms
|
||||
useful for the administration of any JE
|
||||
application, regardless of the API used to build
|
||||
that application.
|
||||
</p>
|
||||
<div class="toc">
|
||||
<p>
|
||||
<b>Table of Contents</b>
|
||||
</p>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="chapter">
|
||||
<a href="backuprestore.html">11. Backing up and Restoring Berkeley DB Java Edition Applications</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="backuprestore.html#databaselogs">Databases and Log Files</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="backuprestore.html#lognames">Log File Overview</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="backuprestore.html#logcleaning">Cleaning the Log Files</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="backuprestore.html#btree">The BTree</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="backuprestore.html#syncs">Database Modifications and Syncs</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="backuprestore.html#normalrecovery">Normal Recovery</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="backup.html">Performing Backups</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="backup.html#partialBackup">Performing a Hot Backup</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="backup.html#completeBackup">Performing an Offline Backup</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="backup.html#dbbackuphelper">Using the DbBackup Helper Class</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="catastrophicrecovery.html">Performing Catastrophic Recovery</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="hotfailover.html">Hot Standby</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="chapter">
|
||||
<a href="administration.html">12. Administering Berkeley DB Java Edition Applications</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="administration.html#propertyfile">The JE Properties File</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="backgroundthreads.html">Managing the Background Threads</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="backgroundthreads.html#cleaner">The Cleaner Thread</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="backgroundthreads.html#checkpointer">The Checkpointer Thread</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="cachesize.html">Sizing the Cache</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="diskthreshold.html">Setting Disk Thresholds</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="commandlinetools.html">The Command Line Tools</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="commandlinetools.html#DbDump">DbDump</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="commandlinetools.html#DbLoad">DbLoad</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="commandlinetools.html#DbVerify">DbVerify</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="managelogging.html">Logging</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="managelogging.html#logginglevels">Managing Logging Levels</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="managelogging.html#handlerlevels">Managing Handler Levels</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
</dl>
|
||||
</dd>
|
||||
</dl>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="indexusage.html">Prev</a> </td>
|
||||
<td width="20%" align="center"> </td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="backuprestore.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Secondary Database Example </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Chapter 11. Backing up and Restoring Berkeley DB Java Edition Applications</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
181
docs/GettingStartedGuide/administration.html
Normal file
181
docs/GettingStartedGuide/administration.html
Normal file
|
|
@ -0,0 +1,181 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Chapter 12. Administering Berkeley DB Java Edition Applications</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="admin.html" title="Part III. Administering JE Applications" />
|
||||
<link rel="prev" href="hotfailover.html" title="Hot Standby" />
|
||||
<link rel="next" href="backgroundthreads.html" title="Managing the Background Threads" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Chapter 12. Administering Berkeley DB Java Edition Applications</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="hotfailover.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Part III. Administering JE Applications</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="backgroundthreads.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="chapter" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title"><a id="administration"></a>Chapter 12. Administering Berkeley DB Java Edition Applications</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="toc">
|
||||
<p>
|
||||
<b>Table of Contents</b>
|
||||
</p>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="administration.html#propertyfile">The JE Properties File</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="backgroundthreads.html">Managing the Background Threads</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="backgroundthreads.html#cleaner">The Cleaner Thread</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="backgroundthreads.html#checkpointer">The Checkpointer Thread</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="cachesize.html">Sizing the Cache</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="diskthreshold.html">Setting Disk Thresholds</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="commandlinetools.html">The Command Line Tools</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="commandlinetools.html#DbDump">DbDump</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="commandlinetools.html#DbLoad">DbLoad</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="commandlinetools.html#DbVerify">DbVerify</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="managelogging.html">Logging</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="managelogging.html#logginglevels">Managing Logging Levels</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="managelogging.html#handlerlevels">Managing Handler Levels</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
</dl>
|
||||
</div>
|
||||
<p>
|
||||
There are a series of tools and parameters of interest to the
|
||||
administrator of a Berkeley DB Java Edition database.
|
||||
These tools and parameters are useful for tuning your
|
||||
JE database's behavior once it is in a production
|
||||
setting, and they are described here. This chapter, however, does not describe backing up and restoring your
|
||||
JE databases. See
|
||||
<a class="xref" href="backuprestore.html" title="Chapter 11. Backing up and Restoring Berkeley DB Java Edition Applications">Backing up and Restoring Berkeley DB Java Edition Applications</a> for information on how to perform those procedures.
|
||||
</p>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="propertyfile"></a>The JE Properties File</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
JE applications can be controlled through a
|
||||
Java properties file. This file must be placed in your environment home directory and it must be named
|
||||
<code class="filename">je.properties</code>.
|
||||
</p>
|
||||
<p>
|
||||
The parameters set in this file take precedence over the configuration behavior coded into the
|
||||
JE application by your application developers.
|
||||
</p>
|
||||
<p>
|
||||
Usually you will use this file to control the behavior of JE's background threads, and to control the size of your
|
||||
in-memory cache. These topics, and the properties parameters related to them, are described in this chapter.
|
||||
Beyond the properties described here, there are other properties identified throughout this manual that may be
|
||||
of interest to you. However, the definitive identification of all
|
||||
the property parameters available to you is described in the javadoc for the
|
||||
<code class="classname">EnvironmentConfig</code> class. Each property has a
|
||||
<code class="classname">String</code> constant in <code class="classname">EnvironmentConfig</code> that
|
||||
describes its meaning, default value, and so forth.
|
||||
</p>
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="hotfailover.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="admin.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="backgroundthreads.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Hot Standby </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Managing the Background Threads</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
628
docs/GettingStartedGuide/applicationoverview.html
Normal file
628
docs/GettingStartedGuide/applicationoverview.html
Normal file
|
|
@ -0,0 +1,628 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>The JE Application</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="introduction.html" title="Chapter 1. Introduction to Berkeley DB Java Edition" />
|
||||
<link rel="prev" href="introduction.html" title="Chapter 1. Introduction to Berkeley DB Java Edition" />
|
||||
<link rel="next" href="restore.html" title="JE Backup and Restore" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">The JE Application</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="introduction.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 1. Introduction to Berkeley DB Java Edition </th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="restore.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="applicationoverview"></a>The JE Application</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="toc">
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="applicationoverview.html#dbIntro">Database Environments</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="applicationoverview.html#key-data">Key-Data Pairs</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="applicationoverview.html#storing-intro">Storing Data</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="applicationoverview.html#duplicatesintro">Duplicate Data</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="applicationoverview.html#replacedeleteIntro">Replacing and Deleting Entries</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="applicationoverview.html#secondary">Secondary Keys</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="applicationoverview.html#transactionIntro">Transactions</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="applicationoverview.html#resourcesIntro">JE Resources</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="applicationoverview.html#applicationConsiderations">
|
||||
Application Considerations
|
||||
</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</div>
|
||||
<p>This section provides a brief overview to the major concepts and
|
||||
operations that comprise a JE application. This section is concluded with a summary of the decisions that
|
||||
you need to make when working with JE.</p>
|
||||
<p>
|
||||
Note that the core JE classes are all contained in the <code class="literal">com.sleepycat.je</code> package.
|
||||
In addition, this book describes some classes that are found in <code class="literal">com.sleepycat.je.bind</code>.
|
||||
The bind APIs are used for converting Java objects in and out of <code class="literal">byte</code> arrays.
|
||||
</p>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="dbIntro"></a>Database Environments</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
Regardless of the JE API that you use, your data is
|
||||
stored in databases. If you use the DPL, you do not manage
|
||||
these databases directly; rather, they are managed for you by
|
||||
the API. On the other hand, if you use the lower-level JE
|
||||
APIs, then you must manage databases directly. This is not
|
||||
difficult to do as it mostly involves opening and closing the
|
||||
databases, giving them names, and so forth. See
|
||||
<a class="xref" href="databases.html" title="Chapter 7. Databases">Databases</a>
|
||||
for more
|
||||
information.
|
||||
</p>
|
||||
<p>
|
||||
That said, JE always requires you to use a
|
||||
<span class="emphasis"><em>database environment</em></span>. Database
|
||||
environments provide an unit of encapsulation for one or more
|
||||
databases. Environments correspond to a directory location on
|
||||
disk, and in them you will find all the files in use by JE.
|
||||
Environments are also used to manage JE resources such as
|
||||
transactions.
|
||||
</p>
|
||||
<p>
|
||||
To use a database environment, it must first be created and then
|
||||
opened. In order to create a database environment, the
|
||||
directory location in which it resides must already exist.
|
||||
</p>
|
||||
<p>
|
||||
You open a database environment by instantiating an
|
||||
<code class="classname">Environment</code> object. Your
|
||||
<code class="classname">Environment</code> instance is called
|
||||
an <span class="emphasis"><em>environment handle</em></span>.
|
||||
</p>
|
||||
<p>
|
||||
|
||||
Once you have opened an environment, what you do with it
|
||||
depends on the nature of your application; that is, the
|
||||
JE API you are using and whether you are using advanced
|
||||
features such as transactions. (See
|
||||
<em class="citetitle">Berkeley DB, Java Edition Getting Started with Transaction Processing</em>
|
||||
for details on using
|
||||
transactions). However, at a minimum you will always have to
|
||||
open your environment before you can access your data stored
|
||||
in JE. Also, before you end your application you should
|
||||
always close your environment.
|
||||
</p>
|
||||
<p>
|
||||
Environments are described in greater detail in <a class="xref" href="env.html" title="Chapter 2. Database Environments">Database Environments</a>.
|
||||
</p>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="key-data"></a>Key-Data Pairs</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
JE stores and retrieves data using
|
||||
<span class="emphasis"><em>key-data pairs</em></span>. The
|
||||
<span class="emphasis"><em>data</em></span> portion of this is the data
|
||||
that you have decided to store in JE for future
|
||||
retrieval. The <span class="emphasis"><em>key</em></span> is the
|
||||
information that you want to use to look up your
|
||||
stored data once it has been placed inside a JE
|
||||
database.
|
||||
</p>
|
||||
<p>
|
||||
For example, if you were building a database that
|
||||
contained employee information, then the
|
||||
<span class="emphasis"><em>data</em></span> portion is all of the
|
||||
information that you want to store about the employees:
|
||||
name, address, phone numbers, physical location, their
|
||||
manager, and so forth.
|
||||
</p>
|
||||
<p>
|
||||
The <span class="emphasis"><em>key</em></span>, however, is the way that
|
||||
you look up any given employee. You can have more than
|
||||
one key if you wish, but every record in your database must have a
|
||||
primary key. If you are using the DPL, then this key must be unique; that is,
|
||||
it must not be used multiple times in the database. However, if you are using
|
||||
the base API, then this requirement is relaxed. See
|
||||
<a class="xref" href="applicationoverview.html#duplicatesintro" title="Duplicate Data">Duplicate Data</a> for more
|
||||
information.
|
||||
</p>
|
||||
<p>
|
||||
For example, in the case of an employee database, you would probably use
|
||||
something like the employee identification number as the primary key as this
|
||||
uniquely identifies a given employee.
|
||||
</p>
|
||||
<p>
|
||||
You can optionally also have secondary keys that represent indexes
|
||||
into your database. These keys do not have to be unique
|
||||
to a given record; in fact, they often are not. For
|
||||
example, you might set up the employee's manager's name
|
||||
as a secondary key so that it is easy to locate all
|
||||
the employee's that work for a given manager.
|
||||
</p>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="storing-intro"></a>Storing Data</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
How you manage your stored information differs
|
||||
significantly, depending on which API you are using.
|
||||
Both APIs ultimately are doing the same thing, but the
|
||||
DPL hides a lot of the details from you.
|
||||
</p>
|
||||
<div class="sect3" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h4 class="title"><a id="dplstore"></a>Storing Data in the DPL</h4>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
The DPL is used to store Java objects in an
|
||||
underlying series of databases. These databases are
|
||||
accessed using an <code class="classname">EntityStore</code>
|
||||
class object.
|
||||
</p>
|
||||
<p>
|
||||
To use the DPL, you must decorate the classes you
|
||||
want to store with Java annotations that identify them
|
||||
as either an <span class="emphasis"><em>entity class</em></span> or a
|
||||
<span class="emphasis"><em>persistent class</em></span>.
|
||||
</p>
|
||||
<p>
|
||||
Entity classes are classes that have a primary key, and
|
||||
optionally one or more secondary keys. That is, these
|
||||
are the classes that you will save and retrieve directly
|
||||
using the DPL. You identify an entity class using the
|
||||
<code class="literal">@Entity</code> java annotation.
|
||||
</p>
|
||||
<p>
|
||||
Persistent classes are classes used by entity classes.
|
||||
They do not have primary or secondary indices used for
|
||||
object retrieval. Rather, they are stored or retrieved
|
||||
when an entity class makes direct use of them. You
|
||||
identify an persistent class using the
|
||||
<code class="literal">@Persistent</code> java annotation.
|
||||
</p>
|
||||
<p>
|
||||
The primary key for an object is obtained from one of the class' data members.
|
||||
You identify which data member to use as the primary key using the
|
||||
<code class="literal">@PrimaryKey</code> java annotation.
|
||||
</p>
|
||||
<p>
|
||||
Note that all non-transient instance fields of a
|
||||
persistent class, as well as its superclasses and
|
||||
subclasses, are persistent. Static and transient fields
|
||||
are not persistent. The persistent fields of a class
|
||||
may be private, package-private (default access),
|
||||
protected or public.
|
||||
</p>
|
||||
<p>
|
||||
|
||||
Also, simple Java types, such as
|
||||
<code class="classname">java.lang.String</code> and
|
||||
<code class="classname">java.util.Date</code>, are automatically handled as a
|
||||
persistent class when you use them in an entity class;
|
||||
you do not have to do anything special to cause these
|
||||
simple Java objects to be stored in the
|
||||
<code class="classname">EntityStore</code>.
|
||||
|
||||
</p>
|
||||
</div>
|
||||
<div class="sect3" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h4 class="title"><a id="lowlevelstore"></a>Storing Data using the Base API</h4>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
When you are not using the DPL, both record keys and record data must be byte
|
||||
arrays and are passed to and returned from JE using
|
||||
<code class="classname">DatabaseEntry</code> instances.
|
||||
<code class="classname">DatabaseEntry</code> only supports storage of Java byte arrays.
|
||||
Complex objects must be marshaled using either Java serialization, or more
|
||||
efficiently with the bind APIs provided with JE </p>
|
||||
<p> Database
|
||||
records and <code class="literal">byte</code> array conversion are described in <a class="xref" href="DBEntry.html" title="Chapter 8. Database Records">Database Records</a>.
|
||||
</p>
|
||||
<p>
|
||||
You store records in a <code class="classname">Database</code> by calling one of the
|
||||
put methods on a <code class="classname">Database</code> handle. JE
|
||||
automatically determines the record's proper placement in the database's
|
||||
internal B-Tree using whatever key and data comparison functions that are
|
||||
available to it.
|
||||
</p>
|
||||
<p>
|
||||
You can also retrieve, or get, records using the
|
||||
<code class="classname">Database</code> handle. Gets are performed by providing the
|
||||
key (and sometimes also the data) of the record that you want to retrieve.
|
||||
</p>
|
||||
<p>
|
||||
You can also use cursors for database puts and gets. Cursors are essentially
|
||||
a mechanism by which you can iterate over the records in the database. Like
|
||||
databases and database environments, cursors must be opened and closed.
|
||||
Cursors are managed using the <code class="classname">Cursor</code> class.
|
||||
</p>
|
||||
<p>
|
||||
Databases are described in <a class="xref" href="databases.html" title="Chapter 7. Databases">Databases</a>. Cursors
|
||||
are described in <a class="xref" href="Cursors.html" title="Chapter 9. Using Cursors">Using Cursors</a>.
|
||||
</p>
|
||||
</div>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="duplicatesintro"></a>Duplicate Data</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
If you are using the base API, then at creation time databases can be configured to
|
||||
allow duplicate data. Remember that JE database records consist of a key/data
|
||||
pair. <span class="emphasis"><em>Duplicate data</em></span>, then, occurs when two or more records have
|
||||
identical keys, but different data. By default, a <code class="classname">Database</code> does
|
||||
not allow duplicate data.
|
||||
</p>
|
||||
<p>
|
||||
If your <code class="classname">Database </code> contains duplicate data, then a simple
|
||||
database get based only on a key returns just the first record that uses that key. To
|
||||
access all duplicate records for that key, you must use a cursor.
|
||||
</p>
|
||||
<p>
|
||||
If you are using the DPL, then you can duplicate date using
|
||||
secondary keys, but not by using the primary key. For more information, see
|
||||
<a class="xref" href="getmultiple.html" title="Retrieving Multiple Objects">Retrieving Multiple Objects</a>.
|
||||
</p>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="replacedeleteIntro"></a>Replacing and Deleting Entries</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
If you are using the DPL, then replacing a stored entity object simply consists of
|
||||
retrieving it, updating it, then storing it again. To delete the object, use the
|
||||
<code class="methodname">delete()</code> method that is available on either its primary or
|
||||
secondary keys. If you use the <code class="methodname">delete()</code> method available on
|
||||
the secondary key, then all objects referenced by that key are also deleted.
|
||||
See <a class="xref" href="dpl_delete.html" title="Deleting Entity Objects">Deleting Entity Objects</a>
|
||||
for more information.
|
||||
</p>
|
||||
<p>
|
||||
If you are using the base API, then how you replace database records depends on whether
|
||||
duplicate data is allowed in the database.
|
||||
</p>
|
||||
<p>
|
||||
If duplicate data is not allowed in the database, then simply calling
|
||||
<code class="methodname">Database.put()</code> with the appropriate key will cause any
|
||||
existing record to be updated with the new data. Similarly, you can delete a record by
|
||||
providing the appropriate key to the <code class="methodname">Database.delete()</code>
|
||||
method.
|
||||
</p>
|
||||
<p>
|
||||
If duplicate data is allowed in the database, then you must position a cursor to the
|
||||
record that you want to update, and then perform the put operation using the cursor.
|
||||
</p>
|
||||
<p>
|
||||
To delete records using the base API, you can use either <code class="methodname">Database.delete()</code> or
|
||||
<code class="methodname">Cursor.delete()</code>. If duplicate data is not allowed in your
|
||||
database, then these two method behave identically. However, if duplicates are allowed
|
||||
in the database, then <code class="methodname">Database.delete()</code> deletes every record
|
||||
that uses the provided key, while <code class="methodname">Cursor.delete()</code> deletes just
|
||||
the record at which the cursor is currently positioned.
|
||||
</p>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="secondary"></a>Secondary Keys</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
Secondary keys provide an alternative way to locate information stored in
|
||||
JE, beyond that which is provided by the primary key. Frequently secondary
|
||||
keys refer to more than one record in the database. In this way, you can find
|
||||
all the cars that are green (if you are maintaining an automotive database) or
|
||||
all the people with brown eyes (if you are maintaining a database about people).
|
||||
In other words, secondary keys represent a index into your data.
|
||||
</p>
|
||||
<p>
|
||||
How you create and maintain secondary keys differs significantly, depending on
|
||||
whether you are using the DPL or the base API.
|
||||
</p>
|
||||
<div class="sect3" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h4 class="title"><a id="secondarydpl"></a>Using Secondaries with the DPL</h4>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
Under the DPL, you declare a particular field to be a secondary key by
|
||||
using the <code class="literal">@SecondaryKey</code> annotation. When you do this,
|
||||
you must declare what kind of an index you are creating. For example,
|
||||
you can declare a secondary key to be part of a
|
||||
<code class="literal">ONE_TO_ONE</code> index, in which case the key is unique to
|
||||
the object. Or you could declare the key to be
|
||||
<code class="literal">MANY_TO_ONE</code>, in which case the key can be used for
|
||||
multiple objects in the data store.
|
||||
</p>
|
||||
<p>
|
||||
Once you have identified secondary keys for a class, you can access
|
||||
those keys by using the <code class="methodname">EntityStore.getSecondaryIndex()</code>
|
||||
method.
|
||||
</p>
|
||||
<p>
|
||||
For more information, see <a class="xref" href="dplindexcreate.html#dplsecondaryidxdecl" title="Declaring Secondary Indexes">Declaring Secondary Indexes</a>.
|
||||
</p>
|
||||
</div>
|
||||
<div class="sect3" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h4 class="title"><a id="secondarybaseapi"></a>Using Secondaries with the Base API.</h4>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
When you are using the base API, you create and maintain secondary keys using a
|
||||
special type of a database, called a <span class="emphasis"><em>secondary database</em></span>.
|
||||
When you are using secondary databases, the database that holds the data you are
|
||||
indexing is called the <span class="emphasis"><em>primary database</em></span>.
|
||||
</p>
|
||||
<p>
|
||||
You create a secondary database by opening it and associating it with an
|
||||
existing primary database. You must also provide a class that generates the
|
||||
secondary's keys (that is, the index) from primary records. Whenever a
|
||||
record in the primary database is added or changed, JE uses this class
|
||||
to determine what the secondary key should be.
|
||||
</p>
|
||||
<p>
|
||||
When a primary record is created, modified, or deleted, JE automatically
|
||||
updates the secondary database(s) for you as is appropriate for the
|
||||
operation performed on the primary.
|
||||
</p>
|
||||
<p>
|
||||
You manage secondary databases using the
|
||||
<code class="classname">SecondaryDatabase</code> class. You identify how to create keys
|
||||
for your secondary databases by supplying an instance of a class that implements
|
||||
the <code class="classname">SecondaryKeyCreator</code> interface.
|
||||
</p>
|
||||
<p>
|
||||
Secondary databases are described in <a class="xref" href="indexes.html" title="Chapter 10. Secondary Databases">Secondary Databases</a>.
|
||||
</p>
|
||||
</div>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="transactionIntro"></a>Transactions</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
Transactions provide a high level of safety for your JE operations by allowing
|
||||
you to manage one or more operations as if they were a single unit of work.
|
||||
Transactions provide your JE operations with recoverability, atomicity, and
|
||||
isolation.
|
||||
</p>
|
||||
<p>
|
||||
Transactions provide recoverability by allowing JE to undo any
|
||||
transactional-protected operations that may have been in progress at the time of an
|
||||
application or system failure.
|
||||
</p>
|
||||
<p>
|
||||
Transactions provide atomicity by allowing you to group many operations into
|
||||
a single unit of work. Either all operations succeed or none of them do. This means
|
||||
that if one write operation fails for any reason, then all other writes contained
|
||||
within that transaction also fail. This ensures that the database is never partially
|
||||
updated as the result of an only partially successful chain of read/write operations.
|
||||
</p>
|
||||
<p>
|
||||
Transactions provide isolation by ensuring that the transaction will never write to a
|
||||
record that is currently in use (for either read or write) by another transaction.
|
||||
Similarly, any record to which the transaction has written can not be read outside of
|
||||
the transaction until the transaction ends. Note that this is only the default
|
||||
behavior; you can configure your <code class="classname">Database</code>,
|
||||
<code class="classname">Cursor</code>, or <code class="classname">Transaction</code> handle to relax
|
||||
its isolation guarantees.
|
||||
</p>
|
||||
<p>
|
||||
Essentially, transactional isolation provides a transaction with the same unmodified view of the
|
||||
database that it would have received had the operations been performed in a single-threaded application.
|
||||
</p>
|
||||
<p>
|
||||
Transactions may be long or short lived, they can encompass as many
|
||||
operations as you want, and (if using the base API) they can span databases
|
||||
so long as all participating databases reside in the same environment.
|
||||
</p>
|
||||
<p>
|
||||
Transaction usage results in a performance penalty for the application because they
|
||||
generally require more disk I/O than do non-transactional operations. Therefore, while
|
||||
most applications will use transactions for JE writes, their usage is optional.
|
||||
In particular, processes that are performing read-only operations
|
||||
might not use transactions. Also, applications that use JE for an easily
|
||||
recreated cache might also choose to avoid transactions.
|
||||
</p>
|
||||
<p>
|
||||
Using transactions with your JE applications is described in detail in the
|
||||
<em class="citetitle">Berkeley DB, Java Edition Getting Started with Transaction Processing</em> guide.
|
||||
</p>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="resourcesIntro"></a>JE Resources</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
JE has some internal resources that you may want to manage. Most important of these is the in-memory cache.
|
||||
You should carefully consider how large the JE cache needs to be. If you set this number too low, JE will
|
||||
perform potentially unnecessary disk I/O which will result in a performance hit. If you set it too high, then
|
||||
you are potentially wasting RAM that could be put to better purposes.
|
||||
</p>
|
||||
<p>
|
||||
Note that the size that you configure for the in-memory cache is a maximum size. At application startup, the
|
||||
cache starts out fairly small (only about 7% of the maximum allowed size for the cache). It then grows as is
|
||||
required by your application's database operations. Also, the cache is not pinned in memory – it can be
|
||||
paged out by your operating system's virtual memory system.
|
||||
</p>
|
||||
<p>
|
||||
Beyond the cache, JE uses several background threads to clean
|
||||
the JE log files, to compress the database by removing unneeded
|
||||
subtrees, and to flush database changes seen in the cache to the backing data files. For the
|
||||
majority of JE applications, the default behavior for the background threads should be acceptable and you
|
||||
will not need to manage their behavior. Note that background threads are started no more than once per
|
||||
process upon environment open.
|
||||
</p>
|
||||
<p>
|
||||
For more information on sizing the cache and on the background threads, see <a class="xref" href="administration.html" title="Chapter 12. Administering Berkeley DB Java Edition Applications">Administering Berkeley DB Java Edition Applications</a>.
|
||||
</p>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="applicationConsiderations"></a>
|
||||
Application Considerations
|
||||
</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>When building your JE application, be sure to think about the following things:</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>What data do you want to store? What is best used for the
|
||||
primary key? What is the best representation for primary record data?
|
||||
If you are using the base API, think about the most efficient way to move your keys and data in and
|
||||
out of byte arrays. See <a class="xref" href="DBEntry.html" title="Chapter 8. Database Records">Database Records</a> for more information.</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>Does the nature of your data require duplicate record support?
|
||||
Remember that duplicate support can be configured only if you are using the base
|
||||
API, and then only at database
|
||||
creation time. See <a class="xref" href="databases.html#DBOpen" title="Opening Databases">Opening Databases</a> for more information.</p>
|
||||
<p>If you are supporting duplicate records, you may also need to think
|
||||
about duplicate comparators (not just key comparators). See
|
||||
<a class="xref" href="comparator.html" title="Using Comparators">Using Comparators</a> for more information.</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>What secondary indexes do you need? How can you compute your secondary indexes based on the data and
|
||||
keys stored in your primary database?
|
||||
Indexes are described in <a class="xref" href="indexes.html" title="Chapter 10. Secondary Databases">Secondary Databases</a>.</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>What cache size do you need? See
|
||||
<a class="xref" href="cachesize.html" title="Sizing the Cache">Sizing the Cache</a> for information on how to size your cache.</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>Does your application require transactions (most will).
|
||||
Transactions are described in the
|
||||
<em class="citetitle">Berkeley DB, Java Edition Getting Started with Transaction Processing</em> guide.
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="introduction.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="introduction.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="restore.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Chapter 1. Introduction to Berkeley DB Java Edition </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> JE Backup and Restore</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
187
docs/GettingStartedGuide/backgroundthreads.html
Normal file
187
docs/GettingStartedGuide/backgroundthreads.html
Normal file
|
|
@ -0,0 +1,187 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Managing the Background Threads</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="administration.html" title="Chapter 12. Administering Berkeley DB Java Edition Applications" />
|
||||
<link rel="prev" href="administration.html" title="Chapter 12. Administering Berkeley DB Java Edition Applications" />
|
||||
<link rel="next" href="cachesize.html" title="Sizing the Cache" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Managing the Background Threads</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="administration.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 12. Administering Berkeley DB Java Edition Applications</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="cachesize.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="backgroundthreads"></a>Managing the Background Threads</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="toc">
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="backgroundthreads.html#cleaner">The Cleaner Thread</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="backgroundthreads.html#checkpointer">The Checkpointer Thread</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</div>
|
||||
<p>
|
||||
JE uses some background threads to keep your database resources within pre-configured limits. If they are
|
||||
going to run, the background threads are started once per application per process. That is, if your application
|
||||
opens the same environment multiple times, the background threads will be started just once for that process.
|
||||
See the following list for the default conditions that gate whether an individual thread is run. Note that you
|
||||
can prevent a background thread from running by using the appropriate <code class="filename">je.properties</code>
|
||||
parameter, but this is not recommended for production use and those parameters are not described here.
|
||||
</p>
|
||||
<p>
|
||||
The background threads are:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
Cleaner thread.
|
||||
</p>
|
||||
<p>
|
||||
Responsible for cleaning and deleting unused log files. See <a class="xref" href="backgroundthreads.html#cleaner" title="The Cleaner Thread">The Cleaner Thread</a> for more information.
|
||||
</p>
|
||||
<p>
|
||||
This thread is run only if the environment is opened for write access.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Compressor thread.
|
||||
</p>
|
||||
<p>
|
||||
Responsible for cleaning up the internal BTree as database records are deleted. The compressor thread
|
||||
ensures that the BTree does not contain unused nodes. There is no need for you to manage the
|
||||
compressor and so it is not described further in this manual.
|
||||
</p>
|
||||
<p>
|
||||
This thread is run only if the environment is opened for write access.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Checkpointer thread.
|
||||
</p>
|
||||
<p>
|
||||
Responsible for running checkpoints on your environment. See
|
||||
<a class="xref" href="backgroundthreads.html#checkpointer" title="The Checkpointer Thread">The Checkpointer Thread</a> for more information.
|
||||
</p>
|
||||
<p>
|
||||
This thread always runs.
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="cleaner"></a>The Cleaner Thread</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
The cleaner thread is responsible for cleaning, or compacting, your log files for you.
|
||||
Log file cleaning is described in <a class="xref" href="backuprestore.html#logcleaning" title="Cleaning the Log Files">Cleaning the Log Files</a>.
|
||||
</p>
|
||||
<p>
|
||||
The following two properties may be of interest to you when managing the cleaner thread:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
<code class="literal">je.cleaner.minUtilization</code>
|
||||
</p>
|
||||
<p>
|
||||
Identifies the percentage of the log file space that must be used for utilized records. If the
|
||||
percentage of log file space used by utilized records is too low, then the cleaner removes
|
||||
obsolete records until this threshold is reached. Default is 50%.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="literal">je.cleaner.expunge</code>
|
||||
</p>
|
||||
<p>
|
||||
Identifies the cleaner's behavior in the event that it is able to remove a log file. If
|
||||
<code class="literal">true</code>, the log files that have been cleaned are deleted from the file system. If
|
||||
<code class="literal">false</code>, the log files that have been cleaned are renamed from
|
||||
<code class="literal">NNNNNNNN.jdb</code> to <code class="literal">NNNNNNNN.del</code>. You are then responsible for
|
||||
deleting the renamed files.
|
||||
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<p>
|
||||
Note that the cleaner thread runs only if the environment is opened for write access. Also, be aware that
|
||||
the cleaner is not guaranteed to finish running before the environment is closed, which can result in
|
||||
unexpectedly large log files. See
|
||||
<a class="xref" href="envclose.html" title="Closing Database Environments">Closing Database Environments</a> for more information.
|
||||
</p>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="checkpointer"></a>The Checkpointer Thread</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
Automatically runs checkpoints. Checkpoints and the administration of this thread are described in
|
||||
the <em class="citetitle">Berkeley DB, Java Edition Getting Started with Transaction Processing</em> guide.
|
||||
</p>
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="administration.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="administration.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="cachesize.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Chapter 12. Administering Berkeley DB Java Edition Applications </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Sizing the Cache</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
291
docs/GettingStartedGuide/backup.html
Normal file
291
docs/GettingStartedGuide/backup.html
Normal file
|
|
@ -0,0 +1,291 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Performing Backups</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="backuprestore.html" title="Chapter 11. Backing up and Restoring Berkeley DB Java Edition Applications" />
|
||||
<link rel="prev" href="backuprestore.html" title="Chapter 11. Backing up and Restoring Berkeley DB Java Edition Applications" />
|
||||
<link rel="next" href="catastrophicrecovery.html" title="Performing Catastrophic Recovery" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Performing Backups</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="backuprestore.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 11. Backing up and Restoring Berkeley DB Java Edition Applications</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="catastrophicrecovery.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="backup"></a>Performing Backups</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="toc">
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="backup.html#partialBackup">Performing a Hot Backup</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="backup.html#completeBackup">Performing an Offline Backup</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="backup.html#dbbackuphelper">Using the DbBackup Helper Class</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</div>
|
||||
<p>
|
||||
This section describes how to backup your JE database(s) such that catastrophic recovery is possible for
|
||||
non-transactional applications. Note that this same material is repeated in the
|
||||
<em class="citetitle">Berkeley DB, Java Edition Getting Started with Transaction Processing</em>
|
||||
guide, but for transactional applications. If you are writing transactional
|
||||
applications, you may want to skip the rest of this chapter and go straight to that book.
|
||||
</p>
|
||||
<p>
|
||||
To backup your database, you can either take a hot backup or an offline backup. A hot
|
||||
backup is performed while database write operations are in progress.
|
||||
</p>
|
||||
<p>
|
||||
Do not confuse hot and offline backups with the concept of a full and incremental backup. Both a
|
||||
hot and an offline backup are full backups – you back up the entire database. The only difference
|
||||
between them is how much of the contents of the in-memory cache are contained in them. On the other hand,
|
||||
an incremental backup is a backup of just those log files modified or created since the time of the last
|
||||
backup. Most backup software
|
||||
is capable of performing both full and incremental backups for you.
|
||||
</p>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="partialBackup"></a>Performing a Hot Backup</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
To perform a hot backup of your JE databases, copy all log files
|
||||
(<code class="filename">*.jdb</code> files) from your environment directory to
|
||||
your archival location or backup media. The files must be copied
|
||||
in alphabetical order (numerical in effect). You do not have to
|
||||
stop any database operations in order to do this.
|
||||
</p>
|
||||
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
|
||||
<h3 class="title">Note</h3>
|
||||
<p>
|
||||
If you are using subdirectories to store your log files, then you must backup
|
||||
the subdirectories, making sure to keep log files in the subdirectory in which
|
||||
JE placed them. For information on using subdirectories to store your log
|
||||
files, see <a class="xref" href="env.html#multisubdir" title="Multiple Environment Subdirectories">Multiple Environment Subdirectories</a>.
|
||||
</p>
|
||||
</div>
|
||||
<p>
|
||||
To make this process a bit easier, you may want to make use of the
|
||||
<code class="classname">DbBackup</code> helper class. See
|
||||
<a class="xref" href="backup.html#dbbackuphelper" title="Using the DbBackup Helper Class">Using the DbBackup Helper Class</a>
|
||||
for details.
|
||||
</p>
|
||||
<p>
|
||||
Note that any modifications made to the database since the time of the last
|
||||
environment sync are not guaranteed to be contained in these log files. In this
|
||||
case, you may want to consider running an offline backup in order to guarantee the
|
||||
availability of all modifications made to your database.
|
||||
</p>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="completeBackup"></a>Performing an Offline Backup</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
An offline backup guarantees that you have captured the database in its entirety, including all contents
|
||||
of your in-memory cache, at the moment that the
|
||||
backup was taken. To do this, you must make sure that no write operations are in progress and all
|
||||
database modifications have been written to your log files
|
||||
on disk. To obtain an offline backup:
|
||||
</p>
|
||||
<div class="orderedlist">
|
||||
<ol type="1">
|
||||
<li>
|
||||
<p>
|
||||
Stop writing your databases.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Run <code class="methodname">Environment.sync()</code> so as to
|
||||
ensure that all database modifications are written to disk. Note that cleanly closing your
|
||||
environment will also ensure that all database modifications are written to disk.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Copy all log files (<code class="filename">*.jdb</code>) from your environment
|
||||
directory to your archival location or backup media. To make this process a
|
||||
bit easier, you may want to make use of the <code class="classname">DbBackup</code>
|
||||
helper class. See the next section for details.
|
||||
</p>
|
||||
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
|
||||
<h3 class="title">Note</h3>
|
||||
<p>
|
||||
If you are using subdirectories to store your log files, then you must backup
|
||||
the subdirectories, making sure to keep log files in the subdirectory in which
|
||||
JE placed them. For information on using subdirectories to store your log
|
||||
files, see <a class="xref" href="env.html#multisubdir" title="Multiple Environment Subdirectories">Multiple Environment Subdirectories</a>.
|
||||
</p>
|
||||
</div>
|
||||
</li>
|
||||
</ol>
|
||||
</div>
|
||||
<p>
|
||||
You can now resume normal database operations.
|
||||
</p>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="dbbackuphelper"></a>Using the DbBackup Helper Class</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
In order to simplify backup operations, JE
|
||||
provides the <code class="classname">DbBackup</code> helper
|
||||
class. This class stops and restarts JE background activity
|
||||
in an open environment. It also lets the application create a
|
||||
backup which can support restoring the environment to
|
||||
a specific point in time.
|
||||
</p>
|
||||
<p>
|
||||
Because you do not have to stop JE write activity
|
||||
in order to take a backup, it is usually necessary to
|
||||
examine your log files twice before you decide that
|
||||
your backup is complete. This is because JE may
|
||||
create a new log file while you are running your
|
||||
backup. A second pass over your log files allows you to
|
||||
ensure that no new files have been created and so you
|
||||
can declare your backup complete.
|
||||
</p>
|
||||
<p>
|
||||
For example:
|
||||
</p>
|
||||
<pre class="programlisting"> time files in activity
|
||||
environment
|
||||
|
||||
t0 000000001.jdb Backup starts copying file 1
|
||||
000000003.jdb
|
||||
000000004.jdb
|
||||
|
||||
t1 000000001.jdb JE log cleaner migrates portion of file 3 to
|
||||
000000004.jdb newly created file 5 and deletes file 3.
|
||||
000000005.jdb Backup finishes file 1, starts copying file 4.
|
||||
Backup MUST include file 5 for a consistent
|
||||
backup!
|
||||
|
||||
t2 000000001.jdb Backup finishes copying file 4, starts and
|
||||
000000004.jdb finishes file 5, has caught up. Backup ends.
|
||||
000000005.jdb
|
||||
</pre>
|
||||
<p>
|
||||
<code class="classname">DbBackup</code> works around this
|
||||
problem by defining the set of files that must be
|
||||
copied for each backup operation, and freezes all
|
||||
changes to those files. The application can copy that
|
||||
defined set of files and finish operation without
|
||||
checking for the ongoing creation of new files. Also,
|
||||
there will be no need to check for a newer version of
|
||||
the last file on the next backup.
|
||||
</p>
|
||||
<p>
|
||||
In the example above, if <code class="classname">DbBackup</code> was used at t0,
|
||||
the application would only have to copy files 1, 3 and
|
||||
4 to back up. On a subsequent backup, the application
|
||||
could start its copying at file 5. There would be no
|
||||
need to check for a newer version of file 4.
|
||||
</p>
|
||||
<p>
|
||||
The following code fragment illustrates this class' usage.
|
||||
See the <code class="classname">DbBackup</code> javadoc for additional
|
||||
examples and more information on incremental backups.
|
||||
</p>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
...
|
||||
import com.sleepycat.je.util.DbBackup;
|
||||
...
|
||||
|
||||
// Find the file number of the last file in the previous backup
|
||||
// persistently, by either checking the backup archive, or saving
|
||||
// state in a persistent file.
|
||||
long lastFileCopiedInPrevBackup = ...
|
||||
|
||||
Environment env = new Environment(...);
|
||||
DbBackup backupHelper = new DbBackup(env, lastFileCopiedInPrevBackup);
|
||||
|
||||
// Start backup, find out what needs to be copied.
|
||||
// If multiple environment subdirectories are in use,
|
||||
// the getLogFilesInBackupSet returns the log file
|
||||
// name prefixed with the dataNNN/ directory in which
|
||||
// it resides.
|
||||
backupHelper.startBackup();
|
||||
try {
|
||||
String[] filesForBackup = backupHelper.getLogFilesInBackupSet();
|
||||
|
||||
// Copy the files to archival storage.
|
||||
myApplicationCopyMethod(filesForBackup)
|
||||
// Update our knowlege of the last file saved in the backup set,
|
||||
// so we can copy less on the next backup
|
||||
lastFileCopiedInPrevBackup = backupHelper.getLastFileInBackupSet();
|
||||
myApplicationSaveLastFile(lastFileCopiedInBackupSet);
|
||||
}
|
||||
finally {
|
||||
// Remember to exit backup mode, or all log files won't be cleaned
|
||||
// and disk usage will bloat.
|
||||
backupHelper.endBackup();
|
||||
} </pre>
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="backuprestore.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="backuprestore.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="catastrophicrecovery.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Chapter 11. Backing up and Restoring Berkeley DB Java Edition Applications </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Performing Catastrophic Recovery</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
355
docs/GettingStartedGuide/backuprestore.html
Normal file
355
docs/GettingStartedGuide/backuprestore.html
Normal file
|
|
@ -0,0 +1,355 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Chapter 11. Backing up and Restoring Berkeley DB Java Edition Applications</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="admin.html" title="Part III. Administering JE Applications" />
|
||||
<link rel="prev" href="admin.html" title="Part III. Administering JE Applications" />
|
||||
<link rel="next" href="backup.html" title="Performing Backups" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Chapter 11. Backing up and Restoring Berkeley DB Java Edition Applications</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="admin.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Part III. Administering JE Applications</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="backup.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="chapter" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title"><a id="backuprestore"></a>Chapter 11. Backing up and Restoring Berkeley DB Java Edition Applications</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="toc">
|
||||
<p>
|
||||
<b>Table of Contents</b>
|
||||
</p>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="backuprestore.html#databaselogs">Databases and Log Files</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="backuprestore.html#lognames">Log File Overview</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="backuprestore.html#logcleaning">Cleaning the Log Files</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="backuprestore.html#btree">The BTree</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="backuprestore.html#syncs">Database Modifications and Syncs</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="backuprestore.html#normalrecovery">Normal Recovery</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="backup.html">Performing Backups</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="backup.html#partialBackup">Performing a Hot Backup</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="backup.html#completeBackup">Performing an Offline Backup</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="backup.html#dbbackuphelper">Using the DbBackup Helper Class</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="catastrophicrecovery.html">Performing Catastrophic Recovery</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="hotfailover.html">Hot Standby</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</div>
|
||||
<p>
|
||||
Fundamentally, you backup your databases by copying JE log files off to a safe storage location. To restore
|
||||
your database from a backup, you copy those files to an appropriate directory on disk and reopen your JE
|
||||
application
|
||||
</p>
|
||||
<p>
|
||||
Beyond these simple activities, there are some differing backup strategies that you may want to consider. These
|
||||
topics are described in this chapter.
|
||||
</p>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="databaselogs"></a>Databases and Log Files</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="toc">
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="backuprestore.html#lognames">Log File Overview</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="backuprestore.html#logcleaning">Cleaning the Log Files</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="backuprestore.html#btree">The BTree</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="backuprestore.html#syncs">Database Modifications and Syncs</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="backuprestore.html#normalrecovery">Normal Recovery</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</div>
|
||||
<p>
|
||||
Before describing JE backup and restore, it is necessary to describe some of JE's internal workings. In
|
||||
particular, a high-level understanding of JE log files and the in-memory cache is required. You also need
|
||||
to understand a little about how JE is using its internal data structures in order to understand why
|
||||
checkpoints and/or syncs are required.
|
||||
</p>
|
||||
<p>
|
||||
You can skip this section so long as you understand that:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
JE databases are stored in log files contained in your environment directory.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Every time a JE environment is opened, normal recovery is run.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
For transactional applications, checkpoints should be run in order to bound normal recovery time.
|
||||
Checkpoints are normally run by the checkpointer thread. Transactional applications and the
|
||||
checkpointer thread are described in the
|
||||
<em class="citetitle">Berkeley DB, Java Edition Getting Started with Transaction Processing</em> guide.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
For non-transactional applications, environment syncs must be performed if you want to guarantee the
|
||||
persistence of your database modifications. Environment syncs are manually performed by the
|
||||
application developer. See <a class="xref" href="usingDbt.html#datapersist" title="Data Persistence">Data Persistence</a> for details.
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="lognames"></a>Log File Overview</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
Your JE database is stored on-disk in a series of log files.
|
||||
JE uses no-overwrite log files, which is to say that JE only ever appends data to the end of a log
|
||||
file. It will never delete or modify an existing log file record.
|
||||
</p>
|
||||
<p>
|
||||
JE log files are named
|
||||
<code class="literal">NNNNNNNN.jdb</code> where <code class="literal">NNNNNNNN</code> is an 8-digit hexadecimal number that
|
||||
increases by 1 (starting from <code class="literal">00000000</code>) for each log file written to disk.
|
||||
</p>
|
||||
<p>
|
||||
JE creates a new log file whenever the current log file has reached a pre-configured size (10000000
|
||||
bytes by default). This size is controlled by the <code class="literal">je.log.fileMax</code> properties
|
||||
parameter. See <a class="xref" href="administration.html#propertyfile" title="The JE Properties File">The JE Properties File</a> for information on setting
|
||||
JE properties.
|
||||
</p>
|
||||
<p>
|
||||
By default, log files are placed in the environment home directory. However, you can
|
||||
cause JE to place log files in subdirectories within the environment home
|
||||
directory. For more information, see
|
||||
<a class="xref" href="env.html#multisubdir" title="Multiple Environment Subdirectories">Multiple Environment Subdirectories</a>.
|
||||
</p>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="logcleaning"></a>Cleaning the Log Files</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
Because JE uses no-overwrite log files, the logs must be compacted or cleaned so as to conserve disk space.
|
||||
</p>
|
||||
<p>
|
||||
JE uses the cleaner background thread to perform this task. When it runs, the cleaner thread picks
|
||||
the log file with the smallest number of active records and scans each log record in it.
|
||||
If the record is no longer
|
||||
active in the database tree, the cleaner does nothing. If the record is still active in the tree, then
|
||||
the cleaner copies the record forward to a newer log file.
|
||||
</p>
|
||||
<p>
|
||||
Once a log file is no longer needed (that is, it no longer contains active records), then the cleaner
|
||||
thread deletes the log file for you. Or, optionally, the cleaner thread can simply rename the discarded
|
||||
log file with a <code class="literal">del</code> suffix.
|
||||
</p>
|
||||
<p>
|
||||
JE uses a minimum log utilization property to determine how much cleaning to perform. The log files
|
||||
contain both obsolete and utilized records. Obsolete records are records that are no longer in use, either
|
||||
because they have been modified or because they have been deleted. Utilized records are those records
|
||||
that are currently in use. The <code class="literal">je.cleaner.minUtilization</code> property identifies the
|
||||
minimum percentage of log space that must be used by utilized records. If this minimum percentage is not
|
||||
met, then log files are cleaned until the minimum percentage is met.
|
||||
</p>
|
||||
<p>
|
||||
For information on managing the cleaner thread, see <a class="xref" href="backgroundthreads.html#cleaner" title="The Cleaner Thread">The Cleaner Thread</a>.
|
||||
</p>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="btree"></a>The BTree</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
JE databases are internally organized as a BTree. In order to operate, JE requires the complete BTree
|
||||
be available to it.
|
||||
</p>
|
||||
<p>
|
||||
When database records are created, modified, or deleted, the modifications are represented in the BTree's
|
||||
leaf nodes. Beyond leaf
|
||||
node changes, database record modifications can also cause changes to other BTree nodes and structures.
|
||||
</p>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="syncs"></a>Database Modifications and Syncs</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
When a write operation is performed in JE, the modified data
|
||||
is written to a leaf node contained in the in-memory cache. If
|
||||
your JE writes are performed without transactions, then the
|
||||
in-memory cache is the only location guaranteed to receive a
|
||||
database modification without further intervention on the part
|
||||
of the application developer.
|
||||
</p>
|
||||
<p>
|
||||
For some class of applications, this lack of a guaranteed write to disk is ideal. By not writing these modifications to
|
||||
the on-disk logs, the application can avoid most of the overhead caused by disk I/O.
|
||||
</p>
|
||||
<p>
|
||||
However, if the application requires its data to persist persist at a specific point in time, then the developer must
|
||||
manually sync database modifications to the on-disk log files (again, this is only necessary for
|
||||
non-transactional applications). This is done using <code class="classname">Environment.sync()</code>.
|
||||
</p>
|
||||
<p>
|
||||
Note that syncing the cache causes JE to write all modified objects in the cache
|
||||
to disk. This is probably the most expensive operation that you can perform in JE.
|
||||
</p>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="normalrecovery"></a>Normal Recovery</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
Every time a JE environment is opened, normal recovery is run.
|
||||
Because of the way that JE organizes and manages its BTrees, all it needs is leaf nodes in order to
|
||||
recreate the rest of the BTree. Essentially, this is what <span class="emphasis"><em>normal recovery</em></span> is
|
||||
doing – recreating any missing parts of the internal BTree from leaf node information stored in the
|
||||
log files.
|
||||
</p>
|
||||
<p>
|
||||
Unlike a traditional database system, JE performs recovery for both transactional
|
||||
and non-transactional operations. The integrity of the Btree is
|
||||
guaranteed by JE in the face of both application and OS crashes.
|
||||
</p>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="admin.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="admin.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="backup.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Part III. Administering JE Applications </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Performing Backups</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
382
docs/GettingStartedGuide/baseapi.html
Normal file
382
docs/GettingStartedGuide/baseapi.html
Normal file
|
|
@ -0,0 +1,382 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Part II. Programming with the Base API</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="prev" href="dpl_exampleinventoryread.html" title="ExampleInventoryRead.java" />
|
||||
<link rel="next" href="databases.html" title="Chapter 7. Databases" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Part II. Programming with the Base API</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="dpl_exampleinventoryread.html">Prev</a> </td>
|
||||
<th width="60%" align="center"> </th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="databases.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="part" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h1 class="title"><a id="baseapi"></a>Part II. Programming with the Base API</h1>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="partintro" lang="en" xml:lang="en">
|
||||
<div></div>
|
||||
<p>
|
||||
This section discusses
|
||||
application that are built using the JE base API. Note that
|
||||
most JE applications can probably be written
|
||||
using the DPL (see <a class="xref" href="dpl.html" title="Part I. Programming with the Direct Persistence Layer">Programming with the Direct Persistence Layer</a> for more
|
||||
information). However, if you are porting an application
|
||||
from the Berkeley DB API, then the base API is right for
|
||||
you.
|
||||
</p>
|
||||
<div class="toc">
|
||||
<p>
|
||||
<b>Table of Contents</b>
|
||||
</p>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="chapter">
|
||||
<a href="databases.html">7. Databases</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="databases.html#DBOpen">Opening Databases</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="databases.html#dwdatabase">Deferred Write Databases</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="databases.html#tempdbje">Temporary Databases</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="databases.html#dbclose">Closing Databases</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="dbprops.html">Database Properties</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="DBAdmin.html">Administrative Methods</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="dbUsage.html">Database Example</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="chapter">
|
||||
<a href="DBEntry.html">8. Database Records</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="DBEntry.html#usingDbEntry">Using Database Records</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="usingDbt.html">Reading and Writing Database Records</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="usingDbt.html#databaseWrite">Writing Records to the Database</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="usingDbt.html#databaseRead">Getting Records from the Database</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="usingDbt.html#recordDelete">Deleting Records</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="usingDbt.html#datapersist">Data Persistence</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="timetolive.html">Using Time to Live</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="timetolive.html#ttl-specify">Specifying a TTL Value</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="timetolive.html#ttl-update">Updating a TTL Value</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="timetolive.html#ttl-remove">Deleting TTL Expiration</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="bindAPI.html">Using the BIND APIs</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="bindAPI.html#bindPrimitive">Numerical and String Objects</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="bindAPI.html#object2dbt">Serializable Complex Objects</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="bindAPI.html#customTuple">Custom Tuple Bindings</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="comparator.html">Using Comparators</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="comparator.html#writeCompare">Writing Comparators</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="comparator.html#setCompare">Setting Comparators</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="dbtUsage.html">Database Record Example</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="chapter">
|
||||
<a href="Cursors.html">9. Using Cursors</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="Cursors.html#openCursor">Opening and Closing Cursors</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="Positioning.html">Getting Records Using the Cursor</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="Positioning.html#diskorderedcursors">Disk Ordered Cursors</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="Positioning.html#cursorsearch">Searching for Records</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="Positioning.html#getdups">Working with Duplicate Records</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="PutEntryWCursor.html">Putting Records Using Cursors</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="DeleteEntryWCursor.html">Deleting Records Using Cursors</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="ReplacingEntryWCursor.html">Replacing Records Using Cursors</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="cursorUsage.html">Cursor Example</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="chapter">
|
||||
<a href="indexes.html">10. Secondary Databases</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="indexes.html#DbAssociate">Opening and Closing Secondary Databases</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="keyCreator.html">Implementing Key
|
||||
<span>Creators</span>
|
||||
|
||||
</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="secondaryProps.html">Secondary Database Properties</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="readSecondary.html">Reading Secondary Databases</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="secondaryDelete.html">Deleting Secondary Database Records</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="secondaryCursor.html">
|
||||
<span>Using Secondary Cursors</span>
|
||||
|
||||
</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="joins.html">Database Joins</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="joins.html#joinUsage">Using Join Cursors</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="joins.html#joinconfig">JoinCursor Properties</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="indexusage.html">Secondary Database Example</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="indexusage.html#secondaryMyDbEnv">Opening Secondary Databases with
|
||||
MyDbEnv</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="indexusage.html#exampleReadSecondaries">Using Secondary Databases with ExampleInventoryRead</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
</dl>
|
||||
</dd>
|
||||
</dl>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="dpl_exampleinventoryread.html">Prev</a> </td>
|
||||
<td width="20%" align="center"> </td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="databases.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">ExampleInventoryRead.java </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Chapter 7. Databases</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
792
docs/GettingStartedGuide/bindAPI.html
Normal file
792
docs/GettingStartedGuide/bindAPI.html
Normal file
|
|
@ -0,0 +1,792 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Using the BIND APIs</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="DBEntry.html" title="Chapter 8. Database Records" />
|
||||
<link rel="prev" href="timetolive.html" title="Using Time to Live" />
|
||||
<link rel="next" href="comparator.html" title="Using Comparators" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Using the BIND APIs</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="timetolive.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 8. Database Records</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="comparator.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="bindAPI"></a>Using the BIND APIs</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="toc">
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="bindAPI.html#bindPrimitive">Numerical and String Objects</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="bindAPI.html#object2dbt">Serializable Complex Objects</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="bindAPI.html#customTuple">Custom Tuple Bindings</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</div>
|
||||
<p>Except for Java String and boolean types, efficiently moving data in
|
||||
and out of Java byte arrays for storage in a database can be a nontrivial
|
||||
operation. To help you with this problem, JE provides the Bind APIs.
|
||||
While these APIs are described in detail in the
|
||||
<span>
|
||||
<em class="citetitle">Berkeley DB, Java Edition Collections Tutorial</em>,
|
||||
</span>
|
||||
|
||||
|
||||
|
||||
this section provides a brief introduction to using the Bind APIs with:</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>Single field numerical and string objects</p>
|
||||
<p>Use this if you want to store a single numerical or string object,
|
||||
such as <code class="classname">Long</code>, <code class="classname">Double</code>, or
|
||||
<code class="classname">String</code>.</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>Complex objects that implement Java serialization.</p>
|
||||
<p>Use this if you are storing objects that implement
|
||||
<code class="classname">Serializable</code> and if you do not need to sort them.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>Non-serialized complex objects.</p>
|
||||
<p>If you are storing objects that do not implement serialization,
|
||||
you can create your own custom tuple bindings. Note that you should
|
||||
use custom tuple bindings even if your objects are serializable if
|
||||
you want to sort on that data.</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="bindPrimitive"></a>Numerical and String Objects</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>You can use the Bind APIs to store primitive data in a <code class="classname">DatabaseEntry</code>
|
||||
object. That is, you can store a single field containing one of the following types:</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
<code class="classname">String</code>
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="classname">Character</code>
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="classname">Boolean</code>
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="classname">Byte</code>
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="classname">Short</code>
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="classname">Integer</code>
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="classname">Long</code>
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="classname">Float</code>
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="classname">Double</code>
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<p>
|
||||
To store primitive data using the Bind APIs:
|
||||
</p>
|
||||
<div class="orderedlist">
|
||||
<ol type="1">
|
||||
<li>
|
||||
<p>Create an <code class="classname">EntryBinding</code> object.</p>
|
||||
<p>When you do this, you use <code class="classname">TupleBinding.getPrimitiveBinding()</code>
|
||||
to return an appropriate binding for the conversion.</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>Use the <code class="classname">EntryBinding</code> object to place
|
||||
the numerical object on the <code class="classname">DatabaseEntry</code>.</p>
|
||||
</li>
|
||||
</ol>
|
||||
</div>
|
||||
<p>Once the data is stored in the DatabaseEntry, you can put it to
|
||||
the database in whatever manner you wish. For example:</p>
|
||||
<a id="je_dbt6"></a>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.bind.EntryBinding;
|
||||
import com.sleepycat.bind.tuple.TupleBinding;
|
||||
import com.sleepycat.je.DatabaseEntry;
|
||||
|
||||
...
|
||||
|
||||
// Need a key for the put.
|
||||
try {
|
||||
String aKey = "myLong";
|
||||
DatabaseEntry theKey = new DatabaseEntry(aKey.getBytes("UTF-8"));
|
||||
|
||||
// Now build the DatabaseEntry using a TupleBinding
|
||||
Long myLong = new Long(123456789l);
|
||||
DatabaseEntry theData = new DatabaseEntry();
|
||||
EntryBinding myBinding = TupleBinding.getPrimitiveBinding(Long.class);
|
||||
myBinding.objectToEntry(myLong, theData);
|
||||
|
||||
// Now store it
|
||||
myDatabase.put(null, theKey, theData);
|
||||
} catch (Exception e) {
|
||||
// Exception handling goes here
|
||||
}</pre>
|
||||
<p>Retrieval from the <code class="classname">DatabaseEntry</code> object is
|
||||
performed in much the same way:</p>
|
||||
<a id="je_dbt7"></a>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.bind.EntryBinding;
|
||||
import com.sleepycat.bind.tuple.TupleBinding;
|
||||
|
||||
import com.sleepycat.je.Database;
|
||||
import com.sleepycat.je.DatabaseEntry;
|
||||
import com.sleepycat.je.LockMode;
|
||||
import com.sleepycat.je.OperationStatus;
|
||||
|
||||
...
|
||||
|
||||
Database myDatabase = null;
|
||||
// Database open omitted for clarity
|
||||
|
||||
try {
|
||||
// Need a key for the get
|
||||
String aKey = "myLong";
|
||||
DatabaseEntry theKey = new DatabaseEntry(aKey.getBytes("UTF-8"));
|
||||
|
||||
// Need a DatabaseEntry to hold the associated data.
|
||||
DatabaseEntry theData = new DatabaseEntry();
|
||||
|
||||
// Bindings need only be created once for a given scope
|
||||
EntryBinding myBinding = TupleBinding.getPrimitiveBinding(Long.class);
|
||||
|
||||
// Get it
|
||||
OperationStatus retVal = myDatabase.get(null, theKey, theData,
|
||||
LockMode.DEFAULT);
|
||||
String retKey = null;
|
||||
if (retVal == OperationStatus.SUCCESS) {
|
||||
// Recreate the data.
|
||||
// Use the binding to convert the byte array contained in theData
|
||||
// to a Long type.
|
||||
Long theLong = (Long) myBinding.entryToObject(theData);
|
||||
retKey = new String(theKey.getData(), "UTF-8");
|
||||
System.out.println("For key: '" + retKey + "' found Long: '" +
|
||||
theLong + "'.");
|
||||
} else {
|
||||
System.out.println("No record found for key '" + retKey + "'.");
|
||||
}
|
||||
} catch (Exception e) {
|
||||
// Exception handling goes here
|
||||
} </pre>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="object2dbt"></a>Serializable Complex Objects</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>Frequently your application requires you to store and manage
|
||||
objects for your record data and/or keys. You may need to do this if you
|
||||
are caching objects created by another process. You may also want to do
|
||||
this if you want to store multiple data values on a record. When used
|
||||
with just primitive data, or with objects containing a single data member,
|
||||
JE database records effectively represent a single row in a two-column table.
|
||||
By storing a complex object in the record, you can turn each record into
|
||||
a single row in an <span class="emphasis"><em>n</em></span>-column table, where
|
||||
<span class="emphasis"><em>n</em></span> is the number of data members contained by the
|
||||
stored object(s).</p>
|
||||
<p>In order to store objects in a
|
||||
JE database, you must convert them to and from a <code class="literal">byte</code> array.
|
||||
The first instinct for many Java programmers is to do this using Java
|
||||
serialization. While this is functionally a correct solution, the result
|
||||
is poor space-performance because this causes the class information
|
||||
to be stored on every such database record. This information can be quite large
|
||||
and it is redundant — the class information does not vary for serialized objects of the same type.
|
||||
</p>
|
||||
<p>
|
||||
In other words, directly using serialization to place your objects into byte
|
||||
arrays means that you will be storing a great deal of unnecessary information in
|
||||
your database, which ultimately leads to larger databases and more expensive disk
|
||||
I/O.
|
||||
</p>
|
||||
<p>The easiest way for you to solve this problem is to use the Bind
|
||||
APIs to perform the serialization for you. Doing so causes the extra
|
||||
object information to be saved off to a unique <code class="classname">Database</code>
|
||||
dedicated for that purpose. This means that you do not have to duplicate
|
||||
that information on each record in the <code class="classname">Database</code>
|
||||
that your application is using to store its information.</p>
|
||||
<p>
|
||||
Note that when you use the Bind APIs to perform serialization, you still
|
||||
receive all the benefits of serialization. You can still use arbitrarily
|
||||
complex object graphs, and you still receive built-in class evolution
|
||||
through the serialVersionUID (SUID) scheme. All of the Java
|
||||
serialization rules apply without modification. For example, you can
|
||||
implement Externalizable instead of Serializable.
|
||||
</p>
|
||||
<div class="sect3" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h4 class="title"><a id="bindCaveats"></a>Usage Caveats</h4>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>Before using the Bind APIs to perform serialization, you may
|
||||
want to consider writing your own custom tuple bindings. Specifically,
|
||||
avoid serialization if:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
If you need to sort based on the objects your are storing.
|
||||
The sort order is meaningless for the byte arrays that you
|
||||
obtain through serialization. Consequently, you should not use serialization for keys if you
|
||||
care about their sort order. You should
|
||||
also not use serialization for record data if your
|
||||
<code class="classname">Database</code> supports duplicate records and you care about sort order.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
You want to minimize the size of your byte arrays. Even when using the Bind APIs to perform the
|
||||
serialization the resulting <code class="literal">byte</code> array may be larger than necessary. You can achieve
|
||||
more compact results by building your own custom tuple binding.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
You want to optimize for speed. In general, custom tuple bindings are faster than serialization at
|
||||
moving data in and out of <code class="literal">byte</code> arrays.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
You are using custom comparators. In JE, comparators are instantiated and called internally whenever
|
||||
databases are not accessible. Because serial bindings depend on the class catalog, a serial binding
|
||||
binding cannot be used during these times. As a result, attempting to use a serial binding with a
|
||||
custom comparator will result in a <code class="literal">NullPointerException</code> during environment open or
|
||||
close.
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<p>
|
||||
For information on building your own custom tuple binding, see <a class="xref" href="bindAPI.html#customTuple" title="Custom Tuple Bindings">Custom Tuple Bindings</a>.
|
||||
</p>
|
||||
</div>
|
||||
<div class="sect3" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h4 class="title"><a id="objectSerial"></a>Serializing Objects</h4>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>To store a serializable complex object using the
|
||||
Bind APIs:</p>
|
||||
<div class="orderedlist">
|
||||
<ol type="1">
|
||||
<li>
|
||||
<p>
|
||||
Implement java.io.Serializable in the class whose instances that
|
||||
you want to store.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>Open (create) your databases. You need two. The first is the
|
||||
database that you use to store your data. The second is used to
|
||||
store the class information.</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>Instantiate a class catalog. You do this with
|
||||
<code class="classname">com.sleepycat.bind.serial.StoredClassCatalog</code>,
|
||||
and at that time you must provide a handle to an open database
|
||||
that is used to store the class information.</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>Create an entry binding that uses <code class="methodname">com.sleepycat.bind.serial.SerialBinding</code>.</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>Instantiate an instance of the object that you want to
|
||||
store, and place it in a <code class="classname">DatabaseEntry</code>
|
||||
using the entry binding that you created in the previous step.</p>
|
||||
</li>
|
||||
</ol>
|
||||
</div>
|
||||
<p>
|
||||
For example, suppose you want to store a long, double, and a
|
||||
String as a record's data. Then you might create a class that
|
||||
looks something like this:
|
||||
</p>
|
||||
<a id="je_dbt8"></a>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
import java.io.Serializable;
|
||||
|
||||
public class MyData implements Serializable {
|
||||
private long longData;
|
||||
private double doubleData;
|
||||
private String description;
|
||||
|
||||
MyData() {
|
||||
longData = 0;
|
||||
doubleData = 0.0;
|
||||
description = null;
|
||||
}
|
||||
|
||||
public void setLong(long data) {
|
||||
longData = data;
|
||||
}
|
||||
|
||||
public void setDouble(double data) {
|
||||
doubleData = data;
|
||||
}
|
||||
|
||||
public void setDescription(String data) {
|
||||
description = data;
|
||||
}
|
||||
|
||||
public long getLong() {
|
||||
return longData;
|
||||
}
|
||||
|
||||
public double getDouble() {
|
||||
return doubleData;
|
||||
}
|
||||
|
||||
public String getDescription() {
|
||||
return description;
|
||||
}
|
||||
}</pre>
|
||||
<p>You can then store instances of this class as follows:</p>
|
||||
<a id="je_dbt9"></a>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.bind.EntryBinding;
|
||||
import com.sleepycat.bind.serial.StoredClassCatalog;
|
||||
import com.sleepycat.bind.serial.SerialBinding;
|
||||
|
||||
import com.sleepycat.je.Database;
|
||||
import com.sleepycat.je.DatabaseConfig;
|
||||
import com.sleepycat.je.DatabaseEntry;
|
||||
|
||||
...
|
||||
|
||||
// The key data.
|
||||
String aKey = "myData";
|
||||
|
||||
// The data data
|
||||
MyData data2Store = new MyData();
|
||||
data2Store.setLong(123456789l);
|
||||
data2Store.setDouble(1234.9876543);
|
||||
data2Store.setDescription("A test instance of this class");
|
||||
|
||||
try {
|
||||
// Environment open omitted for brevity
|
||||
|
||||
// Open the database that you will use to store your data
|
||||
DatabaseConfig myDbConfig = new DatabaseConfig();
|
||||
myDbConfig.setAllowCreate(true);
|
||||
myDbConfig.setSortedDuplicates(true);
|
||||
Database myDatabase = myDbEnv.openDatabase(null, "myDb", myDbConfig);
|
||||
|
||||
// Open the database that you use to store your class information.
|
||||
// The db used to store class information does not require duplicates
|
||||
// support.
|
||||
myDbConfig.setSortedDuplicates(false);
|
||||
Database myClassDb = myDbEnv.openDatabase(null, "classDb",
|
||||
myDbConfig);
|
||||
|
||||
// Instantiate the class catalog
|
||||
StoredClassCatalog classCatalog = new StoredClassCatalog(myClassDb);
|
||||
|
||||
// Create the binding
|
||||
EntryBinding dataBinding = new SerialBinding(classCatalog,
|
||||
MyData.class);
|
||||
|
||||
// Create the DatabaseEntry for the key
|
||||
DatabaseEntry theKey = new DatabaseEntry(aKey.getBytes("UTF-8"));
|
||||
|
||||
// Create the DatabaseEntry for the data. Use the EntryBinding object
|
||||
// that was just created to populate the DatabaseEntry
|
||||
DatabaseEntry theData = new DatabaseEntry();
|
||||
dataBinding.objectToEntry(data2Store, theData);
|
||||
|
||||
// Put it as normal
|
||||
myDatabase.put(null, theKey, theData);
|
||||
|
||||
// Database and environment close omitted for brevity
|
||||
} catch (Exception e) {
|
||||
// Exception handling goes here
|
||||
}</pre>
|
||||
</div>
|
||||
<div class="sect3" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h4 class="title"><a id="objectDeserial"></a>Deserializing Objects</h4>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>Once an object is stored in the database, you can retrieve the
|
||||
<code class="classname">MyData</code> objects from the retrieved
|
||||
<code class="classname">DatabaseEntry</code> using the Bind APIs in much the
|
||||
same way as is described above. For example:</p>
|
||||
<a id="je_dbt10"></a>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.bind.EntryBinding;
|
||||
import com.sleepycat.bind.serial.StoredClassCatalog;
|
||||
import com.sleepycat.bind.serial.SerialBinding;
|
||||
|
||||
import com.sleepycat.je.Database;
|
||||
import com.sleepycat.je.DatabaseConfig;
|
||||
import com.sleepycat.je.DatabaseEntry;
|
||||
import com.sleepycat.je.LockMode;
|
||||
|
||||
...
|
||||
|
||||
// The key data.
|
||||
String aKey = "myData";
|
||||
|
||||
try {
|
||||
// Environment open omitted for brevity.
|
||||
|
||||
// Open the database that stores your data
|
||||
DatabaseConfig myDbConfig = new DatabaseConfig();
|
||||
myDbConfig.setAllowCreate(false);
|
||||
Database myDatabase = myDbEnv.openDatabase(null, "myDb", myDbConfig);
|
||||
|
||||
// Open the database that stores your class information.
|
||||
Database myClassDb = myDbEnv.openDatabase(null, "classDb",
|
||||
myDbConfig);
|
||||
|
||||
// Instantiate the class catalog
|
||||
StoredClassCatalog classCatalog = new StoredClassCatalog(myClassDb);
|
||||
|
||||
// Create the binding
|
||||
EntryBinding dataBinding = new SerialBinding(classCatalog,
|
||||
MyData.class);
|
||||
|
||||
// Create DatabaseEntry objects for the key and data
|
||||
DatabaseEntry theKey = new DatabaseEntry(aKey.getBytes("UTF-8"));
|
||||
DatabaseEntry theData = new DatabaseEntry();
|
||||
|
||||
// Do the get as normal
|
||||
myDatabase.get(null, theKey, theData, LockMode.DEFAULT);
|
||||
|
||||
// Recreate the MyData object from the retrieved DatabaseEntry using
|
||||
// the EntryBinding created above
|
||||
MyData retrievedData = (MyData) dataBinding.entryToObject(theData);
|
||||
|
||||
// Database and environment close omitted for brevity
|
||||
} catch (Exception e) {
|
||||
// Exception handling goes here
|
||||
}</pre>
|
||||
</div>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="customTuple"></a>Custom Tuple Bindings</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
If you want to store complex objects in your database, then you can use
|
||||
tuple bindings to do this. While they are more work to write and
|
||||
maintain than if you were to use serialization, the
|
||||
<code class="literal">byte</code> array conversion is faster. In addition, custom
|
||||
tuple bindings should allow you to create <code class="literal">byte</code> arrays
|
||||
that are smaller than those created by serialization. Custom tuple
|
||||
bindings also allow you to optimize your BTree comparisons, whereas
|
||||
serialization does not.
|
||||
</p>
|
||||
<p>
|
||||
For information on using serialization to store complex objects, see
|
||||
<a class="xref" href="bindAPI.html#object2dbt" title="Serializable Complex Objects">Serializable Complex Objects</a>.
|
||||
</p>
|
||||
<p>To store complex objects using a custom tuple binding:</p>
|
||||
<div class="orderedlist">
|
||||
<ol type="1">
|
||||
<li>
|
||||
<p>Implement the class whose instances that you want to store.
|
||||
Note that you do not have to implement the Serializable interface.</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>Write a tuple binding using the <code class="classname">com.sleepycat.bind.tuple.TupleBinding</code>
|
||||
class.</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>Open (create) your database. Unlike serialization, you only
|
||||
need one.</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>Create an entry binding that uses the tuple binding that you
|
||||
implemented in step 2.</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>Instantiate an instance of the object that you want to store,
|
||||
and place it in a <code class="classname">DatabaseEntry</code> using the
|
||||
entry binding that you created in the previous step.</p>
|
||||
</li>
|
||||
</ol>
|
||||
</div>
|
||||
<p>
|
||||
For example, suppose you want to your keys to be instances of the
|
||||
following class:
|
||||
</p>
|
||||
<a id="je_dbt11"></a>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
public class MyData2 {
|
||||
private long longData;
|
||||
private Double doubleData;
|
||||
private String description;
|
||||
|
||||
public MyData2() {
|
||||
longData = 0;
|
||||
doubleData = new Double(0.0);
|
||||
description = "";
|
||||
}
|
||||
|
||||
public void setLong(long data) {
|
||||
longData = data;
|
||||
}
|
||||
|
||||
public void setDouble(Double data) {
|
||||
doubleData = data;
|
||||
}
|
||||
|
||||
public void setString(String data) {
|
||||
description = data;
|
||||
}
|
||||
|
||||
public long getLong() {
|
||||
return longData;
|
||||
}
|
||||
|
||||
public Double getDouble() {
|
||||
return doubleData;
|
||||
}
|
||||
|
||||
public String getString() {
|
||||
return description;
|
||||
}
|
||||
} </pre>
|
||||
<p>In this case, you need to write a tuple binding for the
|
||||
<code class="classname">MyData2</code> class. When you do this, you must
|
||||
implement the <code class="methodname">TupleBinding.objectToEntry()</code>
|
||||
and <code class="methodname">TupleBinding.entryToObject()</code> abstract methods.
|
||||
Remember the following as you implement these methods:</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>You use <code class="methodname">TupleBinding.objectToEntry()</code> to convert
|
||||
objects to <code class="literal">byte</code> arrays. You use
|
||||
<code class="classname">com.sleepycat.bind.tuple.TupleOutput</code> to write
|
||||
primitive data types to the <code class="literal">byte</code> array. Note that
|
||||
<code class="classname">TupleOutput</code> provides methods that allows
|
||||
you to work with numerical types (<code class="literal">long</code>,
|
||||
<code class="literal">double</code>, <code class="literal">int</code>, and so forth) and
|
||||
not the corresponding <code class="literal">java.lang</code> numerical
|
||||
classes.</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>The order that you write data to the <code class="literal">byte</code>
|
||||
array in <code class="methodname">TupleBinding.objectToEntry()</code> is the order that
|
||||
it appears in the array. So given the <code class="classname">MyData2</code>
|
||||
class as an example, if you write <code class="literal">description</code>,
|
||||
<code class="literal">doubleData</code>, and then <code class="literal">longData</code>,
|
||||
then the resulting byte array will contain these data elements in
|
||||
that order. This means that your records will sort based on the
|
||||
value of the <code class="literal">description</code> data member and then
|
||||
the <code class="literal">doubleData</code> member, and so forth. If you
|
||||
prefer to sort based on, say, the <code class="literal">longData</code> data
|
||||
member, write it to the byte array first.</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>You use <code class="methodname">TupleBinding.entryToObject()</code> to convert
|
||||
the <code class="literal">byte</code> array back into an instance of your
|
||||
original class. You use <code class="classname">com.sleepycat.bind.tuple.TupleInput</code>
|
||||
to get data from the <code class="literal">byte</code> array.</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>The order that you read data from the <code class="literal">byte</code>
|
||||
array must be exactly the same as the order in which it was written.</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<p>For example:</p>
|
||||
<a id="je_dbt12"></a>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.bind.tuple.TupleBinding;
|
||||
import com.sleepycat.bind.tuple.TupleInput;
|
||||
import com.sleepycat.bind.tuple.TupleOutput;
|
||||
|
||||
public class MyTupleBinding extends TupleBinding {
|
||||
|
||||
// Write a MyData2 object to a TupleOutput
|
||||
public void objectToEntry(Object object, TupleOutput to) {
|
||||
|
||||
MyData2 myData = (MyData2)object;
|
||||
|
||||
// Write the data to the TupleOutput (a DatabaseEntry).
|
||||
// Order is important. The first data written will be
|
||||
// the first bytes used by the default comparison routines.
|
||||
to.writeDouble(myData.getDouble().doubleValue());
|
||||
to.writeLong(myData.getLong());
|
||||
to.writeString(myData.getString());
|
||||
}
|
||||
|
||||
// Convert a TupleInput to a MyData2 object
|
||||
public Object entryToObject(TupleInput ti) {
|
||||
|
||||
// Data must be read in the same order that it was
|
||||
// originally written.
|
||||
Double theDouble = new Double(ti.readDouble());
|
||||
long theLong = ti.readLong();
|
||||
String theString = ti.readString();
|
||||
|
||||
MyData2 myData = new MyData2();
|
||||
myData.setDouble(theDouble);
|
||||
myData.setLong(theLong);
|
||||
myData.setString(theString);
|
||||
|
||||
return myData;
|
||||
}
|
||||
} </pre>
|
||||
<p>In order to use the tuple binding, instantiate the binding and
|
||||
then use:</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p><code class="methodname">MyTupleBinding.objectToEntry()</code> to
|
||||
convert a MyData2 object to a <code class="classname">DatabaseEntry</code>.</p>
|
||||
</li>
|
||||
<li>
|
||||
<p><code class="methodname">MyTupleBinding.entryToObject()</code> to convert
|
||||
a <code class="classname">DatabaseEntry</code> to a <code class="classname">MyData2</code>
|
||||
object.</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<p>For example:</p>
|
||||
<a id="je_dbt13"></a>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.bind.tuple.TupleBinding;
|
||||
import com.sleepycat.je.DatabaseEntry;
|
||||
|
||||
...
|
||||
|
||||
TupleBinding keyBinding = new MyTupleBinding();
|
||||
|
||||
MyData2 theKeyData = new MyData2();
|
||||
theKeyData.setLong(123456789l);
|
||||
theKeyData.setDouble(new Double(12345.6789));
|
||||
theKeyData.setString("My key data");
|
||||
|
||||
DatabaseEntry myKey = new DatabaseEntry();
|
||||
|
||||
try {
|
||||
// Store theKeyData in the DatabaseEntry
|
||||
keyBinding.objectToEntry(theKeyData, myKey);
|
||||
|
||||
...
|
||||
// Database put and get activity omitted for clarity
|
||||
...
|
||||
|
||||
// Retrieve the key data
|
||||
theKeyData = (MyData2) keyBinding.entryToObject(myKey);
|
||||
} catch (Exception e) {
|
||||
// Exception handling goes here
|
||||
}</pre>
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="timetolive.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="DBEntry.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="comparator.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Using Time to Live </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Using Comparators</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
131
docs/GettingStartedGuide/cachesize.html
Normal file
131
docs/GettingStartedGuide/cachesize.html
Normal file
|
|
@ -0,0 +1,131 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Sizing the Cache</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="administration.html" title="Chapter 12. Administering Berkeley DB Java Edition Applications" />
|
||||
<link rel="prev" href="backgroundthreads.html" title="Managing the Background Threads" />
|
||||
<link rel="next" href="diskthreshold.html" title="Setting Disk Thresholds" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Sizing the Cache</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="backgroundthreads.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 12. Administering Berkeley DB Java Edition Applications</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="diskthreshold.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="cachesize"></a>Sizing the Cache</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
By default, your cache is limited to a percentage of the JVM maximum
|
||||
memory as specified by the <code class="literal">-Xmx</code> parameter. You can
|
||||
change this percentage by using the <code class="literal">je.maxMemoryPercent</code> property
|
||||
or through <code class="methodname">EnvironmentMutableConfig.setCachePercent()</code>.
|
||||
That is, the maximum amount of memory available to your cache is
|
||||
normally calculated as:
|
||||
</p>
|
||||
<pre class="programlisting">je.maxMemoryPercent * JVM_maximum_memory</pre>
|
||||
<p>
|
||||
You can find out what the value for this property is by using
|
||||
<code class="methodname">EnvironmentConfig.getCachePercent()</code>.
|
||||
</p>
|
||||
<p>
|
||||
Note that you can cause JE to use a fixed maximum cache size by
|
||||
using <code class="literal">je.maxMemory</code> or by using
|
||||
<code class="methodname">EnvironmentConfig.setCacheSize()</code>.
|
||||
</p>
|
||||
<p>
|
||||
Also, not every JVM is capable of identifying the amount of memory requested via
|
||||
the <code class="literal">-Xmx</code> parameter. For those JVMs you must use
|
||||
<code class="literal">je.maxMemory</code> to change your maximum cache size. The
|
||||
default maximum memory available to your cache in this case is 38M.
|
||||
</p>
|
||||
<p>
|
||||
Of the amount of memory allowed for your cache, 93% is used for the internal BTree and the other 7% is
|
||||
used for internal buffers. When your application first starts up, the 7% for buffers is immediately allocated.
|
||||
The remainder of the cache grows lazily as your application reads and writes data.
|
||||
</p>
|
||||
<p>
|
||||
In order for your application to start up successfully, the Java virtual machine must have enough memory
|
||||
available to it (as identified by the <code class="literal">-Xmx</code> command line switch) for both your application and
|
||||
7% of your maximum cache value. In order for your application to run continuously (all the while loading data
|
||||
into the cache), you must make sure your JVM has enough memory for your application plus the maximum cache size.
|
||||
</p>
|
||||
<p>
|
||||
The best way to determine how large your cache needs to be is to put your application into a production
|
||||
environment and watch to see how much disk I/O is occurring. If the application is going to disk quite a lot to
|
||||
retrieve database records, then you should increase the size of your cache (provided that you have enough memory
|
||||
to do so).
|
||||
</p>
|
||||
<p>
|
||||
You can also use the
|
||||
<code class="methodname">com.sleepycat.je.util.DbCacheSize</code> utility
|
||||
to obtain a rough estimate of how large your cache needs to be for
|
||||
a given number of records and record characteristics. The utility
|
||||
returns an estimate of the cache size to hold
|
||||
the specified number of records in memory. See the
|
||||
<a class="ulink" href="../java/com/sleepycat/je/util/DbCacheSize.html" target="_top">DbCacheSize javadoc</a>
|
||||
for information on the utility's usage.
|
||||
</p>
|
||||
<p>
|
||||
In order to determine how frequently your application is going to disk for database records not found in the
|
||||
cache, you can examine the value returned by <code class="methodname">EnvironmentStats.getNCacheMiss()</code>.
|
||||
</p>
|
||||
<p>
|
||||
<code class="methodname">EnvironmentStats.getNCacheMiss()</code> identifies the total number of requests for
|
||||
database objects that were
|
||||
not serviceable from the cache. This value is cumulative since the application started. The faster this number grows,
|
||||
the more your application is going to disk to service database operations. Upon application startup you can
|
||||
expect this value to grow quite rapidly. However, as time passes and your cache is seeded with your most
|
||||
frequently accessed database records, what you want is for this number's growth to be zero or at least very
|
||||
small.
|
||||
</p>
|
||||
<p>
|
||||
Note that this statistic can only be collected from within the application itself or using the JMX extension
|
||||
(see <a class="xref" href="jmx.html" title="JConsole and JMX Support">JConsole and JMX Support</a>).
|
||||
</p>
|
||||
<p>
|
||||
For more information on collecting this statistic, see <a class="xref" href="envStats.html" title="Environment Statistics">Environment Statistics</a>.
|
||||
</p>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="backgroundthreads.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="administration.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="diskthreshold.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Managing the Background Threads </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Setting Disk Thresholds</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
117
docs/GettingStartedGuide/catastrophicrecovery.html
Normal file
117
docs/GettingStartedGuide/catastrophicrecovery.html
Normal file
|
|
@ -0,0 +1,117 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Performing Catastrophic Recovery</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="backuprestore.html" title="Chapter 11. Backing up and Restoring Berkeley DB Java Edition Applications" />
|
||||
<link rel="prev" href="backup.html" title="Performing Backups" />
|
||||
<link rel="next" href="hotfailover.html" title="Hot Standby" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Performing Catastrophic Recovery</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="backup.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 11. Backing up and Restoring Berkeley DB Java Edition Applications</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="hotfailover.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="catastrophicrecovery"></a>Performing Catastrophic Recovery</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
Catastrophic recovery is necessary whenever your environment and/or database have been lost or corrupted
|
||||
due to a media failure (disk failure, for example). Catastrophic recovery is also required if normal
|
||||
recovery fails for any reason.
|
||||
</p>
|
||||
<p>
|
||||
In order to perform catastrophic recovery, you must have a full back up of your databases. You will use
|
||||
this backup to restore your database. See <a class="xref" href="backup.html" title="Performing Backups">Performing Backups</a> for
|
||||
information on running back ups.
|
||||
</p>
|
||||
<p>
|
||||
To perform catastrophic recovery:
|
||||
</p>
|
||||
<div class="orderedlist">
|
||||
<ol type="1">
|
||||
<li>
|
||||
<p>
|
||||
Shut down your application.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Delete the contents of your environment home directory (the one that experienced a catastrophic
|
||||
failure), if there is anything there.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Copy your most recent full backup into your environment home directory.
|
||||
If you are using subdirectories to store your log files, be sure to place
|
||||
the recovered log files back into the subdirectory from which they were
|
||||
originally backed up.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
If you are using a backup utility that runs incremental backups of your
|
||||
environment directory, copy any log files generated since the time of your
|
||||
last full backup. Be sure to restore all log files in the order that they
|
||||
were written. The order is important because it is possible the same log
|
||||
file appears in multiple archives, and you want to run recovery using the
|
||||
most recent version of each log file. Also, if you are using subdirectories to
|
||||
store your log files, be sure to maintain the relationship between your log files
|
||||
and the subdirectory in which JE originally placed them.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Open the environment as normal. JE's normal recovery will run, which will bring your database
|
||||
to a consistent state relative to the changed data found in your log files.
|
||||
</p>
|
||||
</li>
|
||||
</ol>
|
||||
</div>
|
||||
<p>
|
||||
You are now done restoring your database.
|
||||
</p>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="backup.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="backuprestore.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="hotfailover.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Performing Backups </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Hot Standby</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
563
docs/GettingStartedGuide/commandlinetools.html
Normal file
563
docs/GettingStartedGuide/commandlinetools.html
Normal file
|
|
@ -0,0 +1,563 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>The Command Line Tools</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="administration.html" title="Chapter 12. Administering Berkeley DB Java Edition Applications" />
|
||||
<link rel="prev" href="diskthreshold.html" title="Setting Disk Thresholds" />
|
||||
<link rel="next" href="managelogging.html" title="Logging" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">The Command Line Tools</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="diskthreshold.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 12. Administering Berkeley DB Java Edition Applications</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="managelogging.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="commandlinetools"></a>The Command Line Tools</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="toc">
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="commandlinetools.html#DbDump">DbDump</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="commandlinetools.html#DbLoad">DbLoad</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="commandlinetools.html#DbVerify">DbVerify</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</div>
|
||||
<p>
|
||||
JE ships with several command line tools that
|
||||
you can use to help you manage your databases. They are:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
<a class="ulink" href="../java/com/sleepycat/je/util/DbDump.html" target="_top">DbDump</a>
|
||||
</p>
|
||||
<p>
|
||||
Dumps a database to a user-readable format.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<a class="ulink" href="../java/com/sleepycat/je/util/DbLoad.html" target="_top">DbLoad</a>
|
||||
</p>
|
||||
<p>
|
||||
Loads a database from the output produced by <code class="literal">DbDump</code>
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<a class="ulink" href="../java/com/sleepycat/je/util/DbVerify.html" target="_top">DbVerify</a>
|
||||
</p>
|
||||
<p>
|
||||
Verifies the structure of a database.
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="DbDump"></a>DbDump</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
Dumps a database to a flat-text representation. Options are:
|
||||
</p>
|
||||
<div class="variablelist">
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="term">
|
||||
<span class="bold">
|
||||
<strong><code class="option">-f</code> </strong>
|
||||
</span>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<p>
|
||||
Identifies the file to which the output from this command is written.
|
||||
The console (standard out) is used by default.
|
||||
</p>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="term">
|
||||
<span class="bold">
|
||||
<strong><code class="option">-h</code> </strong>
|
||||
</span>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<p>
|
||||
Identifies the environment's directory. This parameter is required.
|
||||
</p>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="term">
|
||||
<span class="bold">
|
||||
<strong><code class="option">-l</code> </strong>
|
||||
</span>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<p>
|
||||
Lists the databases contained in the environment. If the <code class="option">-s</code> is
|
||||
not provided, then this argument is required.
|
||||
</p>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="term">
|
||||
<span class="bold">
|
||||
<strong><code class="option">-p</code> </strong>
|
||||
</span>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<p>
|
||||
Prints database records in human-readable format.
|
||||
</p>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="term">
|
||||
<span class="bold">
|
||||
<strong><code class="option">-r</code> </strong>
|
||||
</span>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<p>
|
||||
Salvage data from a possibly corrupt file. When used on a uncorrupted database, this option
|
||||
should return data equivalent to a normal dump, but most likely in a different order.
|
||||
</p>
|
||||
<p>
|
||||
This option causes the ensuing output to go to a file named
|
||||
<span class="emphasis"><em>dbname</em></span><code class="literal">.dump</code> where
|
||||
<span class="emphasis"><em>dbname</em></span> is the name of the database you are dumping. The
|
||||
file is placed in the current working directory.
|
||||
</p>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="term">
|
||||
<span class="bold">
|
||||
<strong><code class="option">-R</code> </strong>
|
||||
</span>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<p>
|
||||
Aggressively salvage data from a possibly corrupt file. This option differs from the -r option
|
||||
in that it will return all possible data from the file at the risk of also returning already
|
||||
deleted or otherwise nonsensical items. Data dumped in this fashion will almost certainly have
|
||||
to be edited by hand or other means before the data is ready for reload into another database.
|
||||
</p>
|
||||
<p>
|
||||
This option causes the ensuing output to go to a file named
|
||||
<span class="emphasis"><em>dbname</em></span><code class="literal">.dump</code> where
|
||||
<span class="emphasis"><em>dbname</em></span> is the name of the database you are dumping. The
|
||||
file is placed in the current working directory.
|
||||
</p>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="term">
|
||||
<span class="bold">
|
||||
<strong><code class="option">-s</code> </strong>
|
||||
</span>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<p>
|
||||
Identifies the database to be dumped. If this option is not specified, then the <code class="option">-l</code> is required.
|
||||
</p>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="term">
|
||||
<span class="bold">
|
||||
<strong><code class="option">-v</code> </strong>
|
||||
</span>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<p>
|
||||
Prints progress information to the console for
|
||||
<code class="literal">-r</code> or <code class="literal">-R</code> mode.
|
||||
</p>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="term">
|
||||
<span class="bold">
|
||||
<strong><code class="option">-V</code> </strong>
|
||||
</span>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<p>
|
||||
Prints the database version number and then quits. All other command line options are ignored.
|
||||
</p>
|
||||
</dd>
|
||||
</dl>
|
||||
</div>
|
||||
<p>
|
||||
For example:
|
||||
</p>
|
||||
<pre class="programlisting">> <strong class="userinput"><code>java com.sleepycat.je.util.DbDump -h . -p -s VendorDB</code></strong>
|
||||
VERSION=3
|
||||
format=print
|
||||
type=btree
|
||||
database=VendorDB
|
||||
dupsort=false
|
||||
HEADER=END
|
||||
Mom's Kitchen
|
||||
sr\01\01xpt\00\0d53 Yerman Ct.t\00\0c763 554 9200t\00\0bMiddle Townt\00
|
||||
\0eMaggie Kultgent\00\10763 554 9200 x12t\00\02MNt\00\0dMom's Kitchent\00
|
||||
\0555432
|
||||
Off the Vine
|
||||
sr\01\01xpt\00\10133 American Ct.t\00\0c563 121 3800t\00\0aCentennialt\00
|
||||
\08Bob Kingt\00\10563 121 3800 x54t\00\02IAt\00\0cOff the Vinet\00\0552002
|
||||
Simply Fresh
|
||||
sr\01\01xpt\00\1115612 Bogart Lanet\00\0c420 333 3912t\00\08Harrigant\00
|
||||
\0fCheryl Swedbergt\00\0c420 333 3952t\00\02WIt\00\0cSimply Fresht\00\0
|
||||
553704
|
||||
The Baking Pan
|
||||
sr\01\01xpt\00\0e1415 53rd Ave.t\00\0c320 442 2277t\00\07Dutchint\00\09
|
||||
Mike Roant\00\0c320 442 6879t\00\02MNt\00\0eThe Baking Pant\00\0556304
|
||||
The Pantry
|
||||
sr\01\01xpt\00\111206 N. Creek Wayt\00\0c763 555 3391t\00\0bMiddle Town
|
||||
t\00\0fSully Beckstromt\00\0c763 555 3391t\00\02MNt\00\0aThe Pantryt\00
|
||||
\0555432
|
||||
TriCounty Produce
|
||||
sr\01\01xpt\00\12309 S. Main Streett\00\0c763 555 5761t\00\0bMiddle Townt
|
||||
\00\0dMort Dufresnet\00\0c763 555 5765t\00\02MNt\00\11TriCounty Producet
|
||||
\00\0555432
|
||||
DATA=END
|
||||
> </pre>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="DbLoad"></a>DbLoad</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
Loads a database from the output produced by <code class="literal">DbDump</code>.
|
||||
Options are:
|
||||
</p>
|
||||
<div class="variablelist">
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="term">
|
||||
<span class="bold">
|
||||
<strong><code class="option">-c</code> </strong>
|
||||
</span>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<p>Specifies configuration options. The options supplied here override the corresponding options
|
||||
that appear in the data that is being loaded. This option takes values of the form
|
||||
<span class="emphasis"><em>name</em></span>=<span class="emphasis"><em>value</em></span>, where <span class="emphasis"><em>name</em></span>
|
||||
is the configuration option that you are overriding and <span class="emphasis"><em>value</em></span>
|
||||
is the new value for the option.
|
||||
</p>
|
||||
<p>
|
||||
The following options can be specified:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
<code class="literal">database</code>
|
||||
</p>
|
||||
<p>
|
||||
The name of the database to be loaded. This option duplicates the functionality of
|
||||
this command's <code class="option">-s</code> command line option.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="literal">dupsort</code>
|
||||
</p>
|
||||
<p>
|
||||
Indicates whether duplicates are allowed in the database. A value of
|
||||
<code class="literal">true</code> allows duplicates in the database.
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="term">
|
||||
<span class="bold">
|
||||
<strong><code class="option">-f</code> </strong>
|
||||
</span>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<p>
|
||||
Identifies the file from which the database is to be loaded.
|
||||
</p>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="term">
|
||||
<span class="bold">
|
||||
<strong><code class="option">-n</code> </strong>
|
||||
</span>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<p>
|
||||
Do not overwrite existing keys in the database when loading into an already existing database.
|
||||
If a key/data pair cannot be loaded into the database for this reason, a warning message is
|
||||
displayed on the standard error output, and the key/data pair are skipped
|
||||
</p>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="term">
|
||||
<span class="bold">
|
||||
<strong><code class="option">-h</code> </strong>
|
||||
</span>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<p>
|
||||
Identifies the environment's directory. This parameter is required.
|
||||
</p>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="term">
|
||||
<span class="bold">
|
||||
<strong><code class="option">-l</code> </strong>
|
||||
</span>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<p>
|
||||
Allows loading databases that were dumped with the Berkeley DB C
|
||||
product, when the dump file contains parameters not known to JE.
|
||||
</p>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="term">
|
||||
<span class="bold">
|
||||
<strong><code class="option">-s</code> </strong>
|
||||
</span>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<p>
|
||||
Overrides the database name, causing the data to be loaded into a database that uses the name
|
||||
supplied to this parameter.
|
||||
</p>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="term">
|
||||
<span class="bold">
|
||||
<strong><code class="option">-T</code> </strong>
|
||||
</span>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<p>
|
||||
Causes a flat text file to be loaded into the database.
|
||||
</p>
|
||||
<p>
|
||||
The input must be paired lines of text, where the first line of the pair is the key item,
|
||||
and the second line of the pair is its corresponding data item.
|
||||
</p>
|
||||
<p>
|
||||
A simple escape mechanism, where newline and backslash (\) characters are special, is
|
||||
applied to the text input. Newline characters are interpreted as record separators.
|
||||
Backslash characters in the text will be interpreted in one of two ways: If the backslash
|
||||
character precedes another backslash character, the pair will be interpreted as a literal
|
||||
backslash. If the backslash character precedes any other character, the two characters
|
||||
following the backslash will be interpreted as a hexadecimal specification of a single
|
||||
character; for example, \0a is a newline character in the ASCII character set.
|
||||
</p>
|
||||
<p>
|
||||
For this reason, any backslash or newline characters that naturally occur in the text input
|
||||
must be escaped to avoid misinterpretation by db_load.
|
||||
</p>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="term">
|
||||
<span class="bold">
|
||||
<strong><code class="option">-v</code> </strong>
|
||||
</span>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<p>
|
||||
Report periodic load status to the console.
|
||||
</p>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="term">
|
||||
<span class="bold">
|
||||
<strong><code class="option">-V</code> </strong>
|
||||
</span>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<p>
|
||||
Prints the database version number and then quits. All other command line options are ignored.
|
||||
</p>
|
||||
</dd>
|
||||
</dl>
|
||||
</div>
|
||||
<p>
|
||||
For example:
|
||||
</p>
|
||||
<pre class="programlisting">> <strong class="userinput"><code>java com.sleepycat.je.util.DbDump -h . -s VendorDB -f vendordb.txt</code></strong>
|
||||
> <strong class="userinput"><code>java com.sleepycat.je.util.DbLoad -h . -f vendordb.txt</code></strong>
|
||||
> </pre>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="DbVerify"></a>DbVerify</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
Examines the identified database for errors. Options are:
|
||||
</p>
|
||||
<div class="variablelist">
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="term">
|
||||
<span class="bold">
|
||||
<strong><code class="option">-h</code> </strong>
|
||||
</span>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<p>
|
||||
Identifies the environment's directory. This parameter is required.
|
||||
</p>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="term">
|
||||
<span class="bold">
|
||||
<strong><code class="option">-q</code> </strong>
|
||||
</span>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<p>
|
||||
Suppress the printing of any error descriptions. Instead, simply exit success or failure.
|
||||
</p>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="term">
|
||||
<span class="bold">
|
||||
<strong><code class="option">-s</code> </strong>
|
||||
</span>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<p>
|
||||
Identifies the database to be verified. This parameter is required.
|
||||
</p>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="term">
|
||||
<span class="bold">
|
||||
<strong><code class="option">-V</code> </strong>
|
||||
</span>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<p>
|
||||
Prints the database version number and then quits. All other command line options are ignored.
|
||||
</p>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="term">
|
||||
<span class="bold">
|
||||
<strong><code class="option">-v</code> </strong>
|
||||
</span>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<p>
|
||||
Report intermediate statistics every <span class="emphasis"><em>N</em></span> leaf nodes, where
|
||||
<span class="emphasis"><em>N</em></span> is the value that you provide this parameter.
|
||||
</p>
|
||||
</dd>
|
||||
</dl>
|
||||
</div>
|
||||
<p>
|
||||
For example:
|
||||
</p>
|
||||
<pre class="programlisting">> <strong class="userinput"><code>java com.sleepycat.je.util.DbVerify -h . -s VendorDB</code></strong>
|
||||
|
||||
<BtreeStats>
|
||||
<BottomInternalNodesByLevel total="1">
|
||||
<Item level="1" count="1"/>
|
||||
</BottomInternalNodesByLevel>
|
||||
<InternalNodesByLevel total="1">
|
||||
<Item level="2" count="1"/>
|
||||
</InternalNodesByLevel>
|
||||
<LeafNodes count="6"/>
|
||||
<DeletedLeafNodes count="0"/>
|
||||
<DuplicateCountLeafNodes count="0"/>
|
||||
<MainTreeMaxDepth depth="2"/>
|
||||
<DuplicateTreeMaxDepth depth="0"/>
|
||||
</BtreeStats></pre>
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="diskthreshold.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="administration.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="managelogging.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Setting Disk Thresholds </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Logging</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
260
docs/GettingStartedGuide/comparator.html
Normal file
260
docs/GettingStartedGuide/comparator.html
Normal file
|
|
@ -0,0 +1,260 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Using Comparators</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="DBEntry.html" title="Chapter 8. Database Records" />
|
||||
<link rel="prev" href="bindAPI.html" title="Using the BIND APIs" />
|
||||
<link rel="next" href="dbtUsage.html" title="Database Record Example" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Using Comparators</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="bindAPI.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 8. Database Records</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="dbtUsage.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="comparator"></a>Using Comparators</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="toc">
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="comparator.html#writeCompare">Writing Comparators</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="comparator.html#setCompare">Setting Comparators</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</div>
|
||||
<p>Internally, JE databases are organized as BTrees.
|
||||
This means that most database operations
|
||||
(inserts, deletes, reads, and so forth) involve BTree node
|
||||
comparisons. This comparison most frequently occurs based on database
|
||||
keys, but if your database supports duplicate records then
|
||||
comparisons can also occur based on the database data.
|
||||
</p>
|
||||
<p>
|
||||
By default, JE performs all such comparisons using a byte-by-byte
|
||||
lexicographic comparison. This mechanism works well for most data.
|
||||
However, in some cases you may need to specify your own comparison
|
||||
routine. One frequent reason for this is to perform a language sensitive
|
||||
lexical ordering of string keys.
|
||||
</p>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="writeCompare"></a>Writing Comparators</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
You override the default comparison function by providing a Java
|
||||
<code class="classname">Comparator</code> class to the database.
|
||||
The Java <code class="classname">Comparator</code> interface requires you to implement the
|
||||
<code class="methodname">Comparator.compare()</code> method
|
||||
(see <a class="ulink" href="http://java.sun.com/j2se/1.4.2/docs/api/java/util/Comparator.html" target="_top">http://java.sun.com/j2se/1.4.2/docs/api/java/util/Comparator.html</a> for details).
|
||||
</p>
|
||||
<p>
|
||||
JE passes your <code class="methodname">Comparator.compare()</code> method
|
||||
the <code class="literal">byte</code> arrays that you stored in the database. If
|
||||
you know how your data is organized in the <code class="literal">byte</code>
|
||||
array, then you can write a comparison routine that directly examines
|
||||
the contents of the arrays. Otherwise, you have to reconstruct your
|
||||
original objects, and then perform the comparison.
|
||||
</p>
|
||||
<p>
|
||||
For example, suppose you want to perform unicode lexical comparisons
|
||||
instead of UTF-8 byte-by-byte comparisons. Then you could provide a
|
||||
comparator that uses <code class="methodname">String.compareTo()</code>,
|
||||
which performs a Unicode comparison of two strings (note that for
|
||||
single-byte roman characters, Unicode comparison and UTF-8
|
||||
byte-by-byte comparisons are identical – this is something you
|
||||
would only want to do if you were using multibyte unicode characters
|
||||
with JE). In this case, your comparator would look like the
|
||||
following:
|
||||
</p>
|
||||
<a id="je_dbt14"></a>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
import java.util.Comparator;
|
||||
|
||||
public class MyDataComparator implements Comparator {
|
||||
|
||||
public MyDataComparator() {}
|
||||
|
||||
public int compare(Object d1, Object d2) {
|
||||
|
||||
byte[] b1 = (byte[])d1;
|
||||
byte[] b2 = (byte[])d2;
|
||||
|
||||
String s1 = new String(b1, "UTF-8");
|
||||
String s2 = new String(b2, "UTF-8");
|
||||
return s1.compareTo(s2);
|
||||
}
|
||||
} </pre>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="setCompare"></a>Setting Comparators</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
You specify a <code class="classname">Comparator</code> using the following
|
||||
methods. Note that by default these methods can only be used at database
|
||||
creation time, and they are ignored for normal database opens. Also,
|
||||
note that JE uses the no-argument constructor for these comparators.
|
||||
Further, it is not allowable for there to be a mutable state in these
|
||||
comparators or else unpredictable results will occur.
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
<code class="methodname">DatabaseConfig.setBtreeComparator()</code>
|
||||
</p>
|
||||
<p>
|
||||
Sets the Java <code class="classname">Comparator</code> class used
|
||||
to compare two keys in the database.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="methodname">DatabaseConfig.setDuplicateComparator()</code>
|
||||
</p>
|
||||
<p>
|
||||
Sets the Java <code class="classname">Comparator</code> class used to compare the
|
||||
data on two duplicate records in the database. This comparator is
|
||||
used only if the database supports duplicate records.
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<p>
|
||||
You can use the above methods to set a database's comparator after
|
||||
database creation time if you explicitly indicate that the comparator
|
||||
is to be overridden. You do this by using the following methods:
|
||||
</p>
|
||||
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
|
||||
<h3 class="title">Note</h3>
|
||||
<p>
|
||||
If you override your comparator, the new comparator must preserve the
|
||||
sort order implemented by your original comparator. That is, the new
|
||||
comparator and the old comparator must return the same value for the
|
||||
comparison of any two valid objects. Failure to observe this constraint
|
||||
will cause unpredictable results for your application.
|
||||
</p>
|
||||
<p>
|
||||
If you want to change the fundamental sort order for your database, back
|
||||
up the contents of the database, delete the database, recreate it, and
|
||||
then reload its data.
|
||||
</p>
|
||||
</div>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
<code class="methodname">DatabaseConfig.setOverrideBtreeComparator()</code>
|
||||
</p>
|
||||
<p>
|
||||
If set to <code class="literal">true</code>, causes the database's Btree
|
||||
comparator to be overridden with the
|
||||
<code class="classname">Comparator</code> specified on
|
||||
<code class="methodname">DatabaseConfig.setBtreeComparator()</code>. This
|
||||
method can be used to change the comparator post-environment
|
||||
creation.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="methodname">DatabaseConfig.setOverrideDuplicateComparator()</code>
|
||||
</p>
|
||||
<p>
|
||||
If set to <code class="literal">true</code>, causes the database's
|
||||
duplicates comparator to be overridden with the
|
||||
<code class="classname">Comparator</code> specified on
|
||||
<code class="methodname">DatabaseConfig.setDuplicateComparator()</code>.
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<p>For example, to use the <code class="classname">Comparator</code>
|
||||
described in the previous section:</p>
|
||||
<a id="je_dbt15"></a>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.je.Database;
|
||||
import com.sleepycat.je.DatabaseConfig;
|
||||
import com.sleepycat.je.DatabaseException;
|
||||
|
||||
import java.util.Comparator;
|
||||
|
||||
...
|
||||
|
||||
|
||||
// Environment open omitted for brevity
|
||||
|
||||
try {
|
||||
// Get the database configuration object
|
||||
DatabaseConfig myDbConfig = new DatabaseConfig();
|
||||
myDbConfig.setAllowCreate(true);
|
||||
|
||||
// Set the duplicate comparator class
|
||||
myDbConfig.setDuplicateComparator(MyDataComparator.class);
|
||||
|
||||
// Open the database that you will use to store your data
|
||||
myDbConfig.setSortedDuplicates(true);
|
||||
Database myDatabase = myDbEnv.openDatabase(null, "myDb", myDbConfig);
|
||||
} catch (DatabaseException dbe) {
|
||||
// Exception handling goes here
|
||||
}</pre>
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="bindAPI.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="DBEntry.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="dbtUsage.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Using the BIND APIs </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Database Record Example</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
171
docs/GettingStartedGuide/concurrentProcessing.html
Normal file
171
docs/GettingStartedGuide/concurrentProcessing.html
Normal file
|
|
@ -0,0 +1,171 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Appendix A. Concurrent Processing in Berkeley DB Java Edition</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="prev" href="managelogging.html" title="Logging" />
|
||||
<link rel="next" href="multiprocess.html" title="Multiprocess Applications" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Appendix A. Concurrent Processing in Berkeley DB Java Edition</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="managelogging.html">Prev</a> </td>
|
||||
<th width="60%" align="center"> </th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="multiprocess.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="appendix" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title"><a id="concurrentProcessing"></a>Appendix A. Concurrent Processing in Berkeley DB Java Edition</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
An in-depth description of concurrent processing in JE is beyond the scope of this manual. However, there are
|
||||
a few things that you should be aware of as you explore JE. Note that many of these topics are described in
|
||||
greater detail in other parts of this book. This section is intended only to summarize JE concurrent
|
||||
processing.
|
||||
</p>
|
||||
<p>
|
||||
Also, this appendix touches on a topic not
|
||||
discussed in any detail in this manual: transactions. Transactional usage is
|
||||
optional but nevertheless very commonly used for JE
|
||||
applications, especially when writing multi-threaded or
|
||||
multi-process applications. However, transactions also
|
||||
represent a topic that is too large for this book. To read a
|
||||
thorough description of JE and transactional processing,
|
||||
see the <em class="citetitle">Berkeley DB, Java Edition Getting Started with Transaction Processing</em> guide.
|
||||
</p>
|
||||
<p>
|
||||
This appendix first describes concurrency with multithreaded applications. It then goes on to describe
|
||||
<a class="xref" href="multiprocess.html" title="Multiprocess Applications">Multiprocess Applications</a>.
|
||||
</p>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="multithreaded"></a>Multithreaded Applications</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
Note the following if you are writing an application that will use multiple threads for reading and writing
|
||||
JE databases:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
JE database and environment handles are free-threaded (that is, are thread safe), so from a mechanical perspective you
|
||||
do not have to synchronize access to them when they are used by multiple threads of control.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
It is dangerous to close environments and databases when other database operations are in
|
||||
progress. So if you are going to share handles for these objects across threads, you should
|
||||
architect your application such that there is no possibility of a thread closing a handle when
|
||||
another thread is using that handle.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
If a transaction is shared across threads, it is safe to call <code class="methodname">transaction.abort()</code> from
|
||||
any thread. However, be aware that any thread that attempts a database operation using an aborted
|
||||
transaction will throw a <code class="classname">DatabaseException</code>. You should architect your
|
||||
application such that your threads are able to gracefully deal with some other thread aborting the
|
||||
current transaction.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
If a transaction is shared across threads, make sure that
|
||||
<code class="methodname">transaction.commit()</code> can never be called until all threads participating in
|
||||
the transaction have completed their database operations.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Locking is performed at the database record level.
|
||||
JE always checks for lock conflicts, which can be caused either by operations that run for
|
||||
too long a period of time, or by deadlocks. JE decides that a lock conflict has occured when
|
||||
the lock cannot be obtained within a set timeout
|
||||
period. If it cannot, regardless of why the lock could
|
||||
not be obtained, then <code class="classname">LockConflictException</code> is thrown.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
A non-transactional operation that reads a record locks it for the duration of the read.
|
||||
While locked for read, a write lock can not be obtained on that record. However, another read lock
|
||||
can be obtained for that record. This means that for threaded applications, multiple threads can
|
||||
simultaneously read a record, but no thread can write to the record while a read is in progress.
|
||||
</p>
|
||||
<p>
|
||||
Note that if you are performing uncommitted reads, then no locking is performed for that read. Instead,
|
||||
JE uses internal mechanisms to ensure that the data you are reading is consistent (that is, it
|
||||
will not change mid-read).
|
||||
</p>
|
||||
<p>
|
||||
Finally, it is possible to specify that you want a write lock for your read operation. You do this
|
||||
using <code class="literal">LockMode.RMW</code>. Use <code class="literal">RMW</code> when you know that your read will
|
||||
subsequently be followed up with a write operation. Doing so can help to avoid lock conflicts.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
An operation that writes to a record obtains a write lock on that record. While the write lock is in
|
||||
progress, no other locks can be obtained for that record (either read or write).
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
All locks, read or write, obtained from within a transaction are held until the transaction is either
|
||||
committed or aborted.
|
||||
This means that the longer a transaction lives, the more likely other threads in your application
|
||||
are to run into lock conflicts. That is, write operations
|
||||
performed outside of the scope of the transaction will not be able to obtain a lock on those records
|
||||
while the transaction is in progress. Also, by default, reads performed outside the scope of the
|
||||
transaction will not be able to lock records written by the transaction. However, this behavior can be
|
||||
overridden by configuring your reader to perform uncommitted reads.
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="managelogging.html">Prev</a> </td>
|
||||
<td width="20%" align="center"> </td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="multiprocess.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Logging </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Multiprocess Applications</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
284
docs/GettingStartedGuide/cursorUsage.html
Normal file
284
docs/GettingStartedGuide/cursorUsage.html
Normal file
|
|
@ -0,0 +1,284 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Cursor Example</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="Cursors.html" title="Chapter 9. Using Cursors" />
|
||||
<link rel="prev" href="ReplacingEntryWCursor.html" title="Replacing Records Using Cursors" />
|
||||
<link rel="next" href="indexes.html" title="Chapter 10. Secondary Databases" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Cursor Example</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="ReplacingEntryWCursor.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 9. Using Cursors</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="indexes.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="cursorUsage"></a>Cursor Example</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>In <a class="xref" href="dbUsage.html" title="Database Example">Database Example</a> we wrote an
|
||||
application that loaded two <code class="classname">Database</code> objects with vendor
|
||||
and inventory information. In this example, we will use those databases to
|
||||
display all of the items in the inventory database. As a part of showing
|
||||
any given inventory item, we will look up the vendor who can provide the
|
||||
item and show the vendor's contact information.</p>
|
||||
<p>To do this, we create the <code class="classname">ExampleInventoryRead</code>
|
||||
application. This application reads and displays all inventory records by:</p>
|
||||
<div class="orderedlist">
|
||||
<ol type="1">
|
||||
<li>
|
||||
<p>Opening the environment and then the inventory, vendor, and
|
||||
class catalog <code class="classname">Database</code> objects. We do this using the
|
||||
<code class="classname">MyDbEnv</code> class. See <a class="xref" href="dbtUsage.html#dbenvStoredClass" title="Example 8.4 Stored Class Catalog Management with MyDbEnv">Stored Class Catalog Management with MyDbEnv</a>
|
||||
for a description of this class.</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>Obtaining a cursor from the inventory <code class="classname">Database</code>.</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>Steps through the <code class="classname">Database</code>, displaying
|
||||
each record as it goes.</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>To display the Inventory record, the custom tuple binding that
|
||||
we created in <a class="xref" href="dbtUsage.html#InventoryBinding" title="Example 8.3 InventoryBinding.java">InventoryBinding.java</a> is used.</p>
|
||||
</li>
|
||||
<li>
|
||||
<p><code class="methodname">Database.get()</code> is used to obtain the vendor that corresponds to
|
||||
the inventory item.</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>A serial binding is used to convert the
|
||||
<code class="classname">DatabaseEntry</code> returned
|
||||
by the <code class="methodname">get()</code> to a Vendor object.</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>The contents of the Vendor object are displayed.</p>
|
||||
</li>
|
||||
</ol>
|
||||
</div>
|
||||
<p>We implemented the <code class="classname">Vendor</code> class in <a class="xref" href="dbtUsage.html#vendor" title="Example 8.2 Vendor.java">Vendor.java</a>. We implemented the
|
||||
<code class="classname">Inventory</code> class in <a class="xref" href="dbtUsage.html#inventory" title="Example 8.1 Inventory.java">Inventory.java</a>.</p>
|
||||
<p>The full implementation of <code class="classname">ExampleInventoryRead</code>
|
||||
can be found in:
|
||||
</p>
|
||||
<pre class="programlisting"><span class="emphasis"><em>JE_HOME</em></span>/examples/je/gettingStarted/ExampleInventoryRead.java</pre>
|
||||
<p>
|
||||
where <code class="literal"><span class="emphasis"><em>JE_HOME</em></span></code> is the location where you
|
||||
placed your JE
|
||||
distribution.
|
||||
</p>
|
||||
<div class="example">
|
||||
<a id="EIR"></a>
|
||||
<p class="title">
|
||||
<b>Example 9.1 ExampleInventoryRead.java</b>
|
||||
</p>
|
||||
<div class="example-contents">
|
||||
<p>To begin, we import the necessary classes:</p>
|
||||
<a id="je_cursor10"></a>
|
||||
<pre class="programlisting">// file ExampleInventoryRead.java
|
||||
package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.bind.EntryBinding;
|
||||
import com.sleepycat.bind.serial.SerialBinding;
|
||||
import com.sleepycat.bind.tuple.TupleBinding;
|
||||
|
||||
import com.sleepycat.je.Cursor;
|
||||
import com.sleepycat.je.DatabaseEntry;
|
||||
import com.sleepycat.je.DatabaseException;
|
||||
import com.sleepycat.je.LockMode;
|
||||
import com.sleepycat.je.OperationStatus;
|
||||
|
||||
import java.io.File;
|
||||
import java.io.IOException; </pre>
|
||||
<p>Next we declare our class and set up some global variables. Note a
|
||||
<code class="classname">MyDbEnv</code> object is instantiated here. We can do
|
||||
this because its constructor never throws an exception. See <a class="xref" href="dbUsage.html" title="Database Example">Database Example</a> for its implementation
|
||||
details.</p>
|
||||
<a id="je_cursor11"></a>
|
||||
<pre class="programlisting">public class ExampleInventoryRead {
|
||||
|
||||
private static File myDbEnvPath =
|
||||
new File("/tmp/JEDB");
|
||||
|
||||
// Encapsulates the database environment and databases.
|
||||
private static MyDbEnv myDbEnv = new MyDbEnv();
|
||||
|
||||
private static TupleBinding inventoryBinding;
|
||||
private static EntryBinding vendorBinding;</pre>
|
||||
<p>
|
||||
Next we create the <code class="methodname">ExampleInventoryRead.usage()</code> and
|
||||
<code class="methodname">ExampleInventoryRead.main()</code> methods.
|
||||
We perform almost all of our exception handling from <code class="methodname">ExampleInventoryRead.main()</code>, and so we
|
||||
must catch <code class="classname">DatabaseException</code> because the <code class="literal">com.sleepycat.je.*</code>
|
||||
APIs throw them.
|
||||
</p>
|
||||
<a id="je_cursor12"></a>
|
||||
<pre class="programlisting"> private static void usage() {
|
||||
System.out.println("ExampleInventoryRead [-h <env directory>]");
|
||||
System.exit(0);
|
||||
}
|
||||
|
||||
public static void main(String args[]) {
|
||||
ExampleInventoryRead eir = new ExampleInventoryRead();
|
||||
try {
|
||||
eir.run(args);
|
||||
} catch (DatabaseException dbe) {
|
||||
System.err.println("ExampleInventoryRead: " + dbe.toString());
|
||||
dbe.printStackTrace();
|
||||
} finally {
|
||||
myDbEnv.close();
|
||||
}
|
||||
System.out.println("All done.");
|
||||
}</pre>
|
||||
<p>In <code class="methodname">ExampleInventoryRead.run()</code>, we call <code class="methodname">MyDbEnv.setup()</code> to
|
||||
open our environment and databases. Then we create the bindings that we need for using our data objects with
|
||||
<code class="classname">DatabaseEntry</code> objects.
|
||||
</p>
|
||||
<a id="je_cursor13"></a>
|
||||
<pre class="programlisting"> private void run(String args[]) throws DatabaseException {
|
||||
// Parse the arguments list
|
||||
parseArgs(args);
|
||||
|
||||
myDbEnv.setup(myDbEnvPath, // path to the environment home
|
||||
true); // is this environment read-only?
|
||||
|
||||
// Setup our bindings.
|
||||
inventoryBinding = new InventoryBinding();
|
||||
vendorBinding =
|
||||
new SerialBinding(myDbEnv.getClassCatalog(),
|
||||
Vendor.class);
|
||||
showAllInventory();
|
||||
}</pre>
|
||||
<p>Now we write the loop that displays the <code class="classname">Inventory</code>
|
||||
records. We do this by opening a cursor on the inventory database and
|
||||
iterating over all its contents, displaying each as we go.</p>
|
||||
<a id="je_cursor14"></a>
|
||||
<pre class="programlisting"> private void showAllInventory()
|
||||
throws DatabaseException {
|
||||
// Get a cursor
|
||||
Cursor cursor = myDbEnv.getInventoryDB().openCursor(null, null);
|
||||
|
||||
// DatabaseEntry objects used for reading records
|
||||
DatabaseEntry foundKey = new DatabaseEntry();
|
||||
DatabaseEntry foundData = new DatabaseEntry();
|
||||
|
||||
try { // always want to make sure the cursor gets closed.
|
||||
while (cursor.getNext(foundKey, foundData,
|
||||
LockMode.DEFAULT) == OperationStatus.SUCCESS) {
|
||||
Inventory theInventory =
|
||||
(Inventory)inventoryBinding.entryToObject(foundData);
|
||||
displayInventoryRecord(foundKey, theInventory);
|
||||
}
|
||||
} catch (Exception e) {
|
||||
System.err.println("Error on inventory cursor:");
|
||||
System.err.println(e.toString());
|
||||
e.printStackTrace();
|
||||
} finally {
|
||||
cursor.close();
|
||||
}
|
||||
|
||||
} </pre>
|
||||
<p>We use <code class="methodname">ExampleInventoryRead.displayInventoryRecord()</code> to actually show the record. This
|
||||
method first displays all the relevant information from the retrieved
|
||||
Inventory object. It then uses the vendor database to retrieve and
|
||||
display the vendor. Because the vendor database is keyed by vendor name,
|
||||
and because each inventory object contains this key, it is trivial to
|
||||
retrieve the appropriate vendor record.</p>
|
||||
<a id="je_cursor15"></a>
|
||||
<pre class="programlisting"> private void displayInventoryRecord(DatabaseEntry theKey,
|
||||
Inventory theInventory)
|
||||
throws DatabaseException {
|
||||
|
||||
DatabaseEntry searchKey = null;
|
||||
try {
|
||||
String theSKU = new String(theKey.getData(), "UTF-8");
|
||||
System.out.println(theSKU + ":");
|
||||
System.out.println("\t " + theInventory.getItemName());
|
||||
System.out.println("\t " + theInventory.getCategory());
|
||||
System.out.println("\t " + theInventory.getVendor());
|
||||
System.out.println("\t\tNumber in stock: " +
|
||||
theInventory.getVendorInventory());
|
||||
System.out.println("\t\tPrice per unit: " +
|
||||
theInventory.getVendorPrice());
|
||||
System.out.println("\t\tContact: ");
|
||||
|
||||
searchKey =
|
||||
new DatabaseEntry(theInventory.getVendor().getBytes("UTF-8"));
|
||||
} catch (IOException willNeverOccur) {}
|
||||
DatabaseEntry foundVendor = new DatabaseEntry();
|
||||
|
||||
if (myDbEnv.getVendorDB().get(null, searchKey, foundVendor,
|
||||
LockMode.DEFAULT) != OperationStatus.SUCCESS) {
|
||||
System.out.println("Could not find vendor: " +
|
||||
theInventory.getVendor() + ".");
|
||||
System.exit(-1);
|
||||
} else {
|
||||
Vendor theVendor =
|
||||
(Vendor)vendorBinding.entryToObject(foundVendor);
|
||||
System.out.println("\t\t " + theVendor.getAddress());
|
||||
System.out.println("\t\t " + theVendor.getCity() + ", " +
|
||||
theVendor.getState() + " " + theVendor.getZipcode());
|
||||
System.out.println("\t\t Business Phone: " +
|
||||
theVendor.getBusinessPhoneNumber());
|
||||
System.out.println("\t\t Sales Rep: " +
|
||||
theVendor.getRepName());
|
||||
System.out.println("\t\t " +
|
||||
theVendor.getRepPhoneNumber());
|
||||
}
|
||||
}</pre>
|
||||
<p>The remainder of this application provides a utility method used
|
||||
to parse the command line options. From the perspective of this
|
||||
document, this is relatively uninteresting. You can see how this is
|
||||
implemented by looking at:
|
||||
</p>
|
||||
<pre class="programlisting"><span class="emphasis"><em>JE_HOME</em></span>/examples/je/gettingStarted/ExampleInventoryRead.java</pre>
|
||||
<p>
|
||||
where <code class="literal"><span class="emphasis"><em>JE_HOME</em></span></code> is the location where you
|
||||
placed your JE distribution.
|
||||
</p>
|
||||
</div>
|
||||
</div>
|
||||
<br class="example-break" />
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="ReplacingEntryWCursor.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="Cursors.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="indexes.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Replacing Records Using Cursors </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Chapter 10. Secondary Databases</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
119
docs/GettingStartedGuide/dataaccessorclass.html
Normal file
119
docs/GettingStartedGuide/dataaccessorclass.html
Normal file
|
|
@ -0,0 +1,119 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>DataAccessor.java</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="dpl_example.html" title="Chapter 6. A DPL Example" />
|
||||
<link rel="prev" href="mydbenv-persist.html" title="MyDbEnv" />
|
||||
<link rel="next" href="dpl_exampledatabaseput.html" title="ExampleDatabasePut.java" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">DataAccessor.java</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="mydbenv-persist.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 6. A DPL Example</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="dpl_exampledatabaseput.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="dataaccessorclass"></a>DataAccessor.java</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
Now that we have implemented our data classes,
|
||||
we can write a class that will provide
|
||||
convenient access to our primary and
|
||||
secondary indexes.
|
||||
Note that like our data classes, this class is shared by both our
|
||||
example programs.
|
||||
</p>
|
||||
<p>
|
||||
If you compare this class against our
|
||||
<code class="classname">Vendor</code> and
|
||||
<code class="classname">Inventory</code>
|
||||
class implementations, you will see that the
|
||||
primary and secondary indices declared there are
|
||||
referenced by this class.
|
||||
</p>
|
||||
<p>
|
||||
See <a class="xref" href="dpl_example.html#vendorclass" title="Vendor.java">Vendor.java</a>
|
||||
and
|
||||
<a class="xref" href="inventoryclass.html" title="Inventory.java">Inventory.java</a>
|
||||
for those implementations.
|
||||
</p>
|
||||
<pre class="programlisting">package persist.gettingStarted;
|
||||
|
||||
import java.io.File;
|
||||
|
||||
import com.sleepycat.je.DatabaseException;
|
||||
import com.sleepycat.persist.EntityStore;
|
||||
import com.sleepycat.persist.PrimaryIndex;
|
||||
import com.sleepycat.persist.SecondaryIndex;
|
||||
|
||||
public class DataAccessor {
|
||||
// Open the indices
|
||||
public DataAccessor(EntityStore store)
|
||||
throws DatabaseException {
|
||||
|
||||
// Primary key for Inventory classes
|
||||
inventoryBySku = store.getPrimaryIndex(
|
||||
String.class, Inventory.class);
|
||||
|
||||
// Secondary key for Inventory classes
|
||||
// Last field in the getSecondaryIndex() method must be
|
||||
// the name of a class member; in this case, an Inventory.class
|
||||
// data member.
|
||||
inventoryByName = store.getSecondaryIndex(
|
||||
inventoryBySku, String.class, "itemName");
|
||||
|
||||
// Primary key for Vendor class
|
||||
vendorByName = store.getPrimaryIndex(
|
||||
String.class, Vendor.class);
|
||||
}
|
||||
|
||||
// Inventory Accessors
|
||||
PrimaryIndex<String,Inventory> inventoryBySku;
|
||||
SecondaryIndex<String,String,Inventory> inventoryByName;
|
||||
|
||||
// Vendor Accessors
|
||||
PrimaryIndex<String,Vendor> vendorByName;
|
||||
} </pre>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="mydbenv-persist.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="dpl_example.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="dpl_exampledatabaseput.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">MyDbEnv </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> ExampleDatabasePut.java</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
546
docs/GettingStartedGuide/databases.html
Normal file
546
docs/GettingStartedGuide/databases.html
Normal file
|
|
@ -0,0 +1,546 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Chapter 7. Databases</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="baseapi.html" title="Part II. Programming with the Base API" />
|
||||
<link rel="prev" href="baseapi.html" title="Part II. Programming with the Base API" />
|
||||
<link rel="next" href="dbprops.html" title="Database Properties" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Chapter 7. Databases</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="baseapi.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Part II. Programming with the Base API</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="dbprops.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="chapter" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title"><a id="databases"></a>Chapter 7. Databases</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="toc">
|
||||
<p>
|
||||
<b>Table of Contents</b>
|
||||
</p>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="databases.html#DBOpen">Opening Databases</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="databases.html#dwdatabase">Deferred Write Databases</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="databases.html#tempdbje">Temporary Databases</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="databases.html#dbclose">Closing Databases</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="dbprops.html">Database Properties</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="DBAdmin.html">Administrative Methods</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="dbUsage.html">Database Example</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</div>
|
||||
<p>In Berkeley DB Java Edition, a database is a collection of <span class="emphasis"><em>records</em></span>. Records,
|
||||
in turn, consist of key/data pairings.
|
||||
</p>
|
||||
<p>
|
||||
Conceptually, you can think of a
|
||||
<code class="classname">Database</code>
|
||||
|
||||
as containing a two-column table where column 1 contains a key and column 2
|
||||
contains data. Both the key and the data are managed using
|
||||
<code class="classname">DatabaseEntry</code>
|
||||
|
||||
|
||||
<span>class instances</span>
|
||||
|
||||
(see <a class="xref" href="DBEntry.html" title="Chapter 8. Database Records">Database Records</a> for details on this
|
||||
<span>class</span>
|
||||
).
|
||||
So, fundamentally, using a JE
|
||||
<code class="classname">Database</code>
|
||||
|
||||
involves putting, getting, and deleting database records, which in turns involves efficiently
|
||||
managing information
|
||||
<span>encapsulated by </span>
|
||||
|
||||
|
||||
<code class="classname">DatabaseEntry</code>
|
||||
|
||||
|
||||
|
||||
<span>objects.</span>
|
||||
|
||||
The next several chapters of this book are dedicated to those activities.
|
||||
</p>
|
||||
<p>
|
||||
Note that on disk, databases are stored in sequentially numerically
|
||||
named log files in the directory where the opening
|
||||
environment is located. JE log files are described
|
||||
<a class="xref" href="backuprestore.html#databaselogs" title="Databases and Log Files">Databases and Log Files</a>.
|
||||
</p>
|
||||
<p>
|
||||
Also, note that in the previous section of this book, <a class="xref" href="dpl.html" title="Part I. Programming with the Direct Persistence Layer">Programming with the Direct Persistence Layer</a>,
|
||||
we described the DPL The DPL handles all database management
|
||||
for you, including creating all primary and secondary databases as is
|
||||
required by your application. That said, if you are using the DPL
|
||||
you can access the underlying database for a given index if
|
||||
necessary. See the Javadoc for the DPL for more information.
|
||||
</p>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="DBOpen"></a>Opening Databases</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="toc">
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="databases.html#dwdatabase">Deferred Write Databases</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="databases.html#tempdbje">Temporary Databases</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="databases.html#dbclose">Closing Databases</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</div>
|
||||
<p>
|
||||
You open a database by using the
|
||||
<code class="methodname">Environment.openDatabase()</code>
|
||||
method (environments are described in <a class="xref" href="env.html" title="Chapter 2. Database Environments">Database Environments</a>). This
|
||||
method creates and returns a <code class="classname">Database</code>
|
||||
object handle.
|
||||
You must provide <code class="methodname">Environment.openDatabase()</code>
|
||||
with a database name.
|
||||
</p>
|
||||
<p>
|
||||
You can optionally provide <code class="methodname">Environment.openDatabase()</code>
|
||||
with a <code class="classname">DatabaseConfig()</code> object.
|
||||
<code class="classname">DatabaseConfig()</code> allows you to set properties for
|
||||
the database, such as whether it can be created if it does not currently
|
||||
exist, whether you are opening it read-only, and whether the database is to support transactions.
|
||||
</p>
|
||||
<p>
|
||||
Note that by default, JE does not create databases if they do not already exist.
|
||||
To override this behavior, set the <a class="link" href="dbprops.html" title="Database Properties">creation property</a> to true.
|
||||
</p>
|
||||
<p>
|
||||
Finally, if you configured your environment and database to support transactions,
|
||||
you can optionally provide a transaction object to the
|
||||
<code class="methodname">Environment.openDatabase()</code>.
|
||||
Transactions are described in the
|
||||
<em class="citetitle">Berkeley DB, Java Edition Getting Started with Transaction Processing</em> guide.
|
||||
</p>
|
||||
<p>
|
||||
The following code fragment illustrates a database open:
|
||||
<span></span>
|
||||
</p>
|
||||
<a id="je_db1"></a>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.je.Database;
|
||||
import com.sleepycat.je.DatabaseConfig;
|
||||
import com.sleepycat.je.DatabaseException;
|
||||
import com.sleepycat.je.Environment;
|
||||
import com.sleepycat.je.EnvironmentConfig;
|
||||
|
||||
import java.io.File;
|
||||
...
|
||||
|
||||
Environment myDbEnvironment = null;
|
||||
Database myDatabase = null;
|
||||
|
||||
...
|
||||
|
||||
try {
|
||||
// Open the environment. Create it if it does not already exist.
|
||||
EnvironmentConfig envConfig = new EnvironmentConfig();
|
||||
envConfig.setAllowCreate(true);
|
||||
myDbEnvironment = new Environment(new File("/export/dbEnv"),
|
||||
envConfig);
|
||||
|
||||
// Open the database. Create it if it does not already exist.
|
||||
DatabaseConfig dbConfig = new DatabaseConfig();
|
||||
dbConfig.setAllowCreate(true);
|
||||
myDatabase = myDbEnvironment.openDatabase(null,
|
||||
"sampleDatabase",
|
||||
dbConfig);
|
||||
} catch (DatabaseException dbe) {
|
||||
// Exception handling goes here
|
||||
}</pre>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="dwdatabase"></a>Deferred Write Databases</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
By default, JE database operations that modify the
|
||||
database are written (logged) at the time of the operation. For transactional
|
||||
databases, changes become durable when the transaction is committed.
|
||||
</p>
|
||||
<p>
|
||||
However, deferred write databases operations are not written at the time
|
||||
of the operation. Writing is deferred for as long as possible. The
|
||||
changes are only guaranteed to be durable after the
|
||||
<code class="methodname">Database.sync()</code> method
|
||||
is called or the database is properly closed.
|
||||
</p>
|
||||
<p>
|
||||
Deferring writes in this manner has two performance advantages when performing
|
||||
database modifications:
|
||||
</p>
|
||||
<div class="orderedlist">
|
||||
<ol type="1">
|
||||
<li>
|
||||
<p>
|
||||
When multiple threads are performing writes, Concurrency is increased
|
||||
because the bottleneck of writing to the log is avoided.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Less total writing takes place. If a single record is modified more
|
||||
than once, or modified and deleted, then only the final result must
|
||||
be written. If a record is inserted and deleted before a
|
||||
database sync or close occurs, nothing at all is written to disk.
|
||||
The same advantage holds for writing internal index
|
||||
information.
|
||||
</p>
|
||||
</li>
|
||||
</ol>
|
||||
</div>
|
||||
<p>
|
||||
Deferred write databases are useful for applications that perform a
|
||||
great deal of database modifications, record additions, deletions, and
|
||||
so forth. By delaying the data write, you delay the disk I/O. Depending
|
||||
on your workload, this can improve your data throughput by quite a lot.
|
||||
</p>
|
||||
<p>
|
||||
While the durability of a deferred write database is only
|
||||
<span class="emphasis"><em>guaranteed</em></span> when
|
||||
<code class="methodname">Database.sync()</code>
|
||||
is called or the database is properly closed, writing may also occur at other times.
|
||||
For example, a JE checkpoint will effectively perform a
|
||||
<code class="methodname">Database.sync()</code> on all deferred
|
||||
write databases that are open at the time of the checkpoint. If you are
|
||||
using deferred write to load a large data set, and you want to reduce
|
||||
writing as much as possible during the load, consider disabling the JE checkpointer.
|
||||
</p>
|
||||
<p>
|
||||
Also, if the JE cache overflows as database modifications occur, information discarded
|
||||
from the cache is written to disk in order to avoid losing the changes. If you wish to reduce this
|
||||
writing to a minimum, configure your cache to be large enough to hold the entire
|
||||
data set being modified, or as large as possible.
|
||||
</p>
|
||||
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
|
||||
<h3 class="title">Note</h3>
|
||||
<p>
|
||||
Despite the examples noted in the previous paragraphs, there is no guarantee that changes
|
||||
to a deferred write database are durable unless <code class="methodname">Database.sync()</code>
|
||||
is called or the database is closed. If you need guaranteed
|
||||
durability for an operation, consider using transactions instead of deferred write.
|
||||
</p>
|
||||
</div>
|
||||
<p>
|
||||
You should also be aware that <code class="methodname">Database.sync()</code> is a
|
||||
relatively expensive operation because all outstanding changes to the
|
||||
database are written, including internal index information. If you find
|
||||
that you are calling <code class="methodname">Database.sync()</code>
|
||||
frequently, consider using transactions.
|
||||
</p>
|
||||
<p>
|
||||
All other rules of behavior pertain to deferred write databases
|
||||
as they do to normal databases. Deferred write databases must be
|
||||
named and created just as you would a normal database. If you want to
|
||||
delete the deferred write database, you must remove it just as
|
||||
you would a normal database. This is true even if the deferred
|
||||
write database is empty because its name persists in the
|
||||
environment's namespace until such a time as the database is
|
||||
removed.
|
||||
</p>
|
||||
<p>
|
||||
Note that determining whether a database is deferred write is a
|
||||
configuration option. It is therefore possible to switch a
|
||||
database between "normal" mode and deferred write database. You
|
||||
might want to do this if, for example, you want to load a lot
|
||||
of data to the database. In this case, loading data to the
|
||||
database while it is in deferred write state is faster than
|
||||
in "normal" state, because you can avoid a lot of the normal disk
|
||||
I/O overhead during the load process. Once the load is
|
||||
complete, sync the database, close it, and and then reopen it
|
||||
as a normal database. You can then continue operations
|
||||
as if the database had been created as a "normal" database.
|
||||
</p>
|
||||
<p>
|
||||
To configure a database as deferred write, set
|
||||
<code class="methodname">DatabaseConfig.setDeferredWrite()</code>
|
||||
to <code class="literal">true</code> and then open the database with
|
||||
that <code class="classname">DatabaseConfig</code> option.
|
||||
</p>
|
||||
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
|
||||
<h3 class="title">Note</h3>
|
||||
<p>
|
||||
If you are using the DPL, then you configure your entire
|
||||
store to be deferred write using
|
||||
<code class="methodname">StoreConfig.setDeferredWrite()</code>.
|
||||
You can also sync every database in your store using
|
||||
<code class="methodname">EntityStore.sync()</code>.
|
||||
</p>
|
||||
</div>
|
||||
<p>
|
||||
For example, the following code fragment opens and closes a
|
||||
deferred write database:
|
||||
</p>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.je.Database;
|
||||
import com.sleepycat.je.DatabaseConfig;
|
||||
import com.sleepycat.je.DatabaseException;
|
||||
import com.sleepycat.je.Environment;
|
||||
import com.sleepycat.je.EnvironmentConfig;
|
||||
|
||||
import java.io.File;
|
||||
...
|
||||
|
||||
Environment myDbEnvironment = null;
|
||||
Database myDatabase = null;
|
||||
|
||||
...
|
||||
|
||||
try {
|
||||
// Open the environment. Create it if it does not already exist.
|
||||
EnvironmentConfig envConfig = new EnvironmentConfig();
|
||||
envConfig.setAllowCreate(true);
|
||||
myDbEnvironment = new Environment(new File("/export/dbEnv"),
|
||||
envConfig);
|
||||
|
||||
// Open the database. Create it if it does not already exist.
|
||||
DatabaseConfig dbConfig = new DatabaseConfig();
|
||||
dbConfig.setAllowCreate(true);
|
||||
// Make it deferred write
|
||||
dbConfig.setDeferredWrite(true);
|
||||
myDatabase = myDbEnvironment.openDatabase(null,
|
||||
"sampleDatabase",
|
||||
dbConfig);
|
||||
|
||||
...
|
||||
// do work
|
||||
...
|
||||
// Do this when you want the work to be persistent at a
|
||||
// specific point, prior to closing the database.
|
||||
myDatabase.sync();
|
||||
|
||||
// then close the database and environment here
|
||||
// (described later in this chapter).
|
||||
|
||||
} catch (DatabaseException dbe) {
|
||||
// Exception handling goes here
|
||||
}</pre>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="tempdbje"></a>Temporary Databases</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
By default, all JE databases are durable; that is, the data that you put in them
|
||||
will remain in them across program runs, unless you explicitly delete the data.
|
||||
However, it is possible to configure a
|
||||
<span class="emphasis"><em>temporary</em></span> database that is not durable. A temporary database is
|
||||
automatically deleted when it is closed or after a crash occurs.
|
||||
</p>
|
||||
<p>
|
||||
Temporary databases are essentially in-memory only databases. Therefore,
|
||||
they are particularly useful for applications that want databases which
|
||||
are truly temporary.
|
||||
</p>
|
||||
<p>
|
||||
Note that temporary databases do not always avoid disk I/O. It is particularly
|
||||
important to realize that temporary databases can page to disk if the cache is not
|
||||
large enough to hold the database's entire contents. Therefore, temporary database
|
||||
performance is best when your in-memory cache is large enough to hold the database's
|
||||
entire data-set.
|
||||
</p>
|
||||
<p>
|
||||
A temporary database operates internally in deferred write mode and has
|
||||
the same performance advantages as described above for deferred write
|
||||
databases (see <a class="xref" href="databases.html#dwdatabase" title="Deferred Write Databases">Deferred Write Databases</a>).
|
||||
However, unlike deferred write databases, a temporary database is not written
|
||||
during checkpoints and this provides an additional performance advantage.
|
||||
</p>
|
||||
<p>
|
||||
Temporary databases must be named and created just as you would a normal database.
|
||||
To configure a database as temporary, set
|
||||
<code class="methodname">DatabaseConfig.setTemporary</code> to
|
||||
<code class="literal">true</code> and then open the database with that
|
||||
<code class="classname">DatabaseConfig</code> instance.
|
||||
</p>
|
||||
<p>
|
||||
For example:
|
||||
</p>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.je.Database;
|
||||
import com.sleepycat.je.DatabaseConfig;
|
||||
import com.sleepycat.je.DatabaseException;
|
||||
import com.sleepycat.je.Environment;
|
||||
import com.sleepycat.je.EnvironmentConfig;
|
||||
|
||||
import java.io.File;
|
||||
...
|
||||
|
||||
Environment myDbEnvironment = null;
|
||||
Database myDatabase = null;
|
||||
|
||||
...
|
||||
|
||||
try {
|
||||
// Open the environment. Create it if it does not already exist.
|
||||
EnvironmentConfig envConfig = new EnvironmentConfig();
|
||||
envConfig.setAllowCreate(true);
|
||||
myDbEnvironment = new Environment(new File("/export/dbEnv"),
|
||||
envConfig);
|
||||
|
||||
// Open the database. Create it if it does not already exist.
|
||||
DatabaseConfig dbConfig = new DatabaseConfig();
|
||||
dbConfig.setAllowCreate(true);
|
||||
// Make it a temporary database
|
||||
dbConfig.setTemporary(true);
|
||||
myDatabase = myDbEnvironment.openDatabase(null,
|
||||
"sampleDatabase",
|
||||
dbConfig);
|
||||
|
||||
...
|
||||
// do work
|
||||
...
|
||||
|
||||
// then close the database and environment here
|
||||
// (see the next section)
|
||||
|
||||
} catch (DatabaseException dbe) {
|
||||
// Exception handling goes here
|
||||
}</pre>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="dbclose"></a>Closing Databases</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>Once you are done using the database, you must close it. You use the
|
||||
<code class="methodname">Database.close()</code> method to do this.</p>
|
||||
<p>Closing a database causes it to become unusable until it is opened
|
||||
again. If any cursors are opened for the database,
|
||||
JE warns you about the open cursors, and then closes them for you.
|
||||
Active cursors during a database
|
||||
close can cause unexpected results, especially if any of those cursors are
|
||||
writing to the database in another thread. You should always make sure that all your
|
||||
database accesses have completed before closing your database.</p>
|
||||
<p>It is recommended that you close all your
|
||||
databases before closing the environment to which they belong.</p>
|
||||
<p>Cursors are described in <a class="xref" href="Cursors.html" title="Chapter 9. Using Cursors">Using Cursors</a> later in this manual.</p>
|
||||
<p>
|
||||
The following illustrates database and environment close:
|
||||
</p>
|
||||
<a id="je_db2"></a>
|
||||
<pre class="programlisting">import com.sleepycat.je.DatabaseException;
|
||||
import com.sleepycat.je.Database;
|
||||
import com.sleepycat.je.Environment;
|
||||
|
||||
...
|
||||
|
||||
try {
|
||||
if (myDatabase != null) {
|
||||
myDatabase.close();
|
||||
}
|
||||
|
||||
if (myDbEnvironment != null) {
|
||||
myDbEnvironment.close();
|
||||
}
|
||||
} catch (DatabaseException dbe) {
|
||||
// Exception handling goes here
|
||||
} </pre>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="baseapi.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="baseapi.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="dbprops.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Part II. Programming with the Base API </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Database Properties</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
203
docs/GettingStartedGuide/dbUsage.html
Normal file
203
docs/GettingStartedGuide/dbUsage.html
Normal file
|
|
@ -0,0 +1,203 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Database Example</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="databases.html" title="Chapter 7. Databases" />
|
||||
<link rel="prev" href="DBAdmin.html" title="Administrative Methods" />
|
||||
<link rel="next" href="DBEntry.html" title="Chapter 8. Database Records" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Database Example</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="DBAdmin.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 7. Databases</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="DBEntry.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="dbUsage"></a>Database Example</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>In <a class="xref" href="dbenvUsageExample.html" title="Database Environment Management Example">Database Environment Management Example</a> we created a class that manages an
|
||||
<code class="classname">Environment</code>. We now extend that class to allow it
|
||||
to open and manage multiple databases. Again, remember that you can find
|
||||
this class in:
|
||||
</p>
|
||||
<pre class="programlisting"><span class="emphasis"><em>JE_HOME</em></span>/je/gettingStarted/MyDbEnv.java</pre>
|
||||
<p>
|
||||
where <code class="literal"><span class="emphasis"><em>JE_HOME</em></span></code> is the location where you
|
||||
placed your JE distribution.
|
||||
</p>
|
||||
<div class="example">
|
||||
<a id="mydbenvWDatabase"></a>
|
||||
<p class="title">
|
||||
<b>Example 7.1 Database Management with MyDbEnv</b>
|
||||
</p>
|
||||
<div class="example-contents">
|
||||
<p>First, we need to import a few additional classes, and setup some global variables to support databases.
|
||||
The databases that we are configuring and creating here are used by applications developed in examples later in this guide.</p>
|
||||
<a id="je_db10"></a>
|
||||
<pre class="programlisting">// File MyDbEnv.java
|
||||
|
||||
package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.je.DatabaseException;
|
||||
<strong class="userinput"><code>import com.sleepycat.je.DatabaseConfig;
|
||||
import com.sleepycat.je.Database; </code></strong>
|
||||
import com.sleepycat.je.EnvironmentConfig;
|
||||
import com.sleepycat.je.Environment;
|
||||
|
||||
import java.io.File;
|
||||
|
||||
public class MyDbEnv {
|
||||
|
||||
private Environment myEnv;
|
||||
<strong class="userinput"><code>private Database vendorDb;
|
||||
private Database inventoryDb;</code></strong>
|
||||
|
||||
public MyDbEnv() {} </pre>
|
||||
<p>
|
||||
|
||||
Next we need to update the <code class="methodname">MyDbEnv.setup()</code> method to instantiate a
|
||||
<code class="classname">DatabaseConfig</code> object. We also need to set some properties on that object. These property
|
||||
values are determined by the value of the <code class="literal">readOnly</code> parameter. We want our databases to be
|
||||
read-only if the environment is also read-only. We also want to allow our databases to be created if the databases
|
||||
are not read-only.
|
||||
|
||||
</p>
|
||||
<a id="je_db11"></a>
|
||||
<pre class="programlisting"> public void setup(File envHome, boolean readOnly)
|
||||
throws DatabaseException {
|
||||
|
||||
// Instantiate an environment <strong class="userinput"><code>and database</code></strong> configuration object
|
||||
EnvironmentConfig myEnvConfig = new EnvironmentConfig();
|
||||
<strong class="userinput"><code>DatabaseConfig myDbConfig = new DatabaseConfig();</code></strong>
|
||||
// Configure the environment <strong class="userinput"><code>and databases</code></strong> for the read-only
|
||||
// state as identified by the readOnly parameter on this
|
||||
// method call.
|
||||
myEnvConfig.setReadOnly(readOnly);
|
||||
<strong class="userinput"><code>myDbConfig.setReadOnly(readOnly);</code></strong>
|
||||
// If the environment is opened for write, then we want to be
|
||||
// able to create the environment <strong class="userinput"><code>and databases</code></strong> if
|
||||
// they do not exist.
|
||||
myEnvConfig.setAllowCreate(!readOnly);
|
||||
<strong class="userinput"><code>myDbConfig.setAllowCreate(!readOnly);</code></strong>
|
||||
|
||||
// Instantiate the Environment. This opens it and also possibly
|
||||
// creates it.
|
||||
myEnv = new Environment(envHome, myEnvConfig);
|
||||
|
||||
<strong class="userinput"><code>// Now create and open our databases.
|
||||
vendorDb = myEnv.openDatabase(null,
|
||||
"VendorDB",
|
||||
myDbConfig);
|
||||
|
||||
inventoryDb = myEnv.openDatabase(null,
|
||||
"InventoryDB",
|
||||
myDbConfig);</code></strong>
|
||||
} </pre>
|
||||
<p>
|
||||
Next we need some additional getter methods used to return our database handles.
|
||||
</p>
|
||||
<a id="je_db12"></a>
|
||||
<pre class="programlisting"> // Getter methods
|
||||
public Environment getEnvironment() {
|
||||
return myEnv;
|
||||
}
|
||||
|
||||
<strong class="userinput"><code>public Database getVendorDB() {
|
||||
return vendorDb;
|
||||
}
|
||||
|
||||
public Database getInventoryDB() {
|
||||
return inventoryDb;
|
||||
}</code></strong> </pre>
|
||||
<p>
|
||||
Finally, we need to update the <code class="methodname">MyDbEnv.close()</code> method to close our databases.
|
||||
</p>
|
||||
<a id="je_db13"></a>
|
||||
<pre class="programlisting"> // Close the environment
|
||||
public void close() {
|
||||
if (myEnv != null) {
|
||||
try {
|
||||
<strong class="userinput"><code>vendorDb.close();
|
||||
inventoryDb.close();</code></strong>
|
||||
myEnv.close();
|
||||
} catch(DatabaseException dbe) {
|
||||
System.err.println("Error closing MyDbEnv: " +
|
||||
dbe.toString());
|
||||
System.exit(-1);
|
||||
}
|
||||
}
|
||||
}
|
||||
}</pre>
|
||||
<p>We can now use <code class="classname">MyDbEnv</code> to open and close
|
||||
both database environments and databases from the appropriate place in
|
||||
our application. For example:</p>
|
||||
<a id="je_db14"></a>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.je.DatabaseException;
|
||||
<strong class="userinput"><code>import com.sleepycat.je.Database;</code></strong>
|
||||
|
||||
import java.io.File;
|
||||
|
||||
...
|
||||
|
||||
MyDbEnv exampleDbEnv = new MyDbEnv();
|
||||
|
||||
try {
|
||||
exampleDbEnv.setup(new File("/directory/currently/exists"), true);
|
||||
<strong class="userinput"><code>Database vendorDb = exampleDbEnv.getVendorDB();
|
||||
Database inventoryDB = exampleDbEnv.getInventoryDB();</code></strong>
|
||||
|
||||
...
|
||||
|
||||
} catch(DatabaseException dbe) {
|
||||
// Error code goes here
|
||||
} finally {
|
||||
exampleDbEnv.close();
|
||||
} </pre>
|
||||
</div>
|
||||
</div>
|
||||
<br class="example-break" />
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="DBAdmin.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="databases.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="DBEntry.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Administrative Methods </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Chapter 8. Database Records</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
180
docs/GettingStartedGuide/dbenvUsageExample.html
Normal file
180
docs/GettingStartedGuide/dbenvUsageExample.html
Normal file
|
|
@ -0,0 +1,180 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Database Environment Management Example</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="env.html" title="Chapter 2. Database Environments" />
|
||||
<link rel="prev" href="envStats.html" title="Environment Statistics" />
|
||||
<link rel="next" href="dpl.html" title="Part I. Programming with the Direct Persistence Layer" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Database Environment Management Example</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="envStats.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 2. Database Environments</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="dpl.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="dbenvUsageExample"></a>Database Environment Management Example</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
This example provides a complete class that can open and close an environment. It is
|
||||
both extended and used in subsequent examples in this book to open and close both
|
||||
environments and databases. We do this so as to make the example code
|
||||
shorter and easier to manage. You can find this class in:
|
||||
</p>
|
||||
<pre class="programlisting"><span class="emphasis"><em>JE_HOME</em></span>/examples/je/gettingStarted/MyDbEnv.java</pre>
|
||||
<p>
|
||||
where <code class="literal"><span class="emphasis"><em>JE_HOME</em></span></code> is the location where you
|
||||
placed your JE distribution.
|
||||
</p>
|
||||
<div class="example">
|
||||
<a id="mydbenv"></a>
|
||||
<p class="title">
|
||||
<b>Example 2.1 Database Environment Management Class</b>
|
||||
</p>
|
||||
<div class="example-contents">
|
||||
<p>First we write the normal class declarations. We also set up some
|
||||
private data members that are used to manage environment creation. We
|
||||
use the class constructor to instantiate the <code class="classname">EnvironmentConfig</code>
|
||||
object that is used to configure our environment when we open it.</p>
|
||||
<a id="je_env6"></a>
|
||||
<pre class="programlisting">// File MyDbEnv.java
|
||||
package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.je.DatabaseException;
|
||||
import com.sleepycat.je.Environment;
|
||||
import com.sleepycat.je.EnvironmentConfig;
|
||||
|
||||
import java.io.File;
|
||||
|
||||
|
||||
public class MyDbEnv {
|
||||
|
||||
private Environment myEnv;
|
||||
|
||||
public MyDbEnv() {} </pre>
|
||||
<p>Next we need a method to open the environment. This is responsible
|
||||
for instantiating our <code class="classname">Environment</code> object.
|
||||
Remember that instantiation is what opens the environment (or creates it
|
||||
if the creation property is set to <code class="literal">true</code> and the
|
||||
environment does not currently exist).
|
||||
</p>
|
||||
<a id="je_env7"></a>
|
||||
<pre class="programlisting"> public void setup(File envHome, boolean readOnly)
|
||||
throws DatabaseException {
|
||||
|
||||
// Instantiate an environment configuration object
|
||||
EnvironmentConfig myEnvConfig = new EnvironmentConfig();
|
||||
// Configure the environment for the read-only state as identified
|
||||
// by the readOnly parameter on this method call.
|
||||
myEnvConfig.setReadOnly(readOnly);
|
||||
// If the environment is opened for write, then we want to be
|
||||
// able to create the environment if it does not exist.
|
||||
myEnvConfig.setAllowCreate(!readOnly);
|
||||
|
||||
// Instantiate the Environment. This opens it and also possibly
|
||||
// creates it.
|
||||
myEnv = new Environment(envHome, myEnvConfig);
|
||||
} </pre>
|
||||
<p>
|
||||
Next we provide a getter method that allows us to retrieve the
|
||||
<code class="classname">Environment</code> directly. This is needed for later
|
||||
examples in this guide.
|
||||
</p>
|
||||
<a id="je_env8"></a>
|
||||
<pre class="programlisting"> // Getter methods
|
||||
public Environment getEnv() {
|
||||
return myEnv;
|
||||
} </pre>
|
||||
<p>Finally, we need a method to close our <code class="classname">Environment</code>.
|
||||
We wrap this operation in a <code class="literal">try</code> block so that it can
|
||||
be used gracefully in a <code class="literal">finally</code> statement.</p>
|
||||
<a id="je_env9"></a>
|
||||
<pre class="programlisting"> // Close the environment
|
||||
public void close() {
|
||||
if (myEnv != null) {
|
||||
try {
|
||||
myEnv.close();
|
||||
} catch(DatabaseException dbe) {
|
||||
System.err.println("Error closing environment" +
|
||||
dbe.toString());
|
||||
}
|
||||
}
|
||||
}
|
||||
} </pre>
|
||||
<p>
|
||||
This completes the <code class="classname">MyDbEnv</code> class. While not particularly useful
|
||||
as it currently exists, we will build upon it throughout this book so that it will
|
||||
eventually open and close all of the entity stores or databases required by our
|
||||
applications.
|
||||
</p>
|
||||
<p>
|
||||
We can now use <code class="classname">MyDbEnv</code> to open and close a database environment
|
||||
from the appropriate place in our application. For example:
|
||||
</p>
|
||||
<a id="je_env10"></a>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.je.DatabaseEntry;
|
||||
import com.sleepycat.je.DatabaseException;
|
||||
|
||||
import java.io.File;
|
||||
|
||||
...
|
||||
|
||||
MyDbEnv exampleDbEnv = new MyDbEnv();
|
||||
|
||||
try {
|
||||
exampleDbEnv.setup(new File("/directory/currently/exists"), true);
|
||||
...
|
||||
|
||||
} catch(DatabaseException dbe) {
|
||||
// Error code goes here
|
||||
} finally {
|
||||
exampleDbEnv.close();
|
||||
} </pre>
|
||||
</div>
|
||||
</div>
|
||||
<br class="example-break" />
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="envStats.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="env.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="dpl.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Environment Statistics </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Part I. Programming with the Direct Persistence Layer</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
164
docs/GettingStartedGuide/dbprops.html
Normal file
164
docs/GettingStartedGuide/dbprops.html
Normal file
|
|
@ -0,0 +1,164 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Database Properties</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="databases.html" title="Chapter 7. Databases" />
|
||||
<link rel="prev" href="databases.html" title="Chapter 7. Databases" />
|
||||
<link rel="next" href="DBAdmin.html" title="Administrative Methods" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Database Properties</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="databases.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 7. Databases</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="DBAdmin.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="dbprops"></a>Database Properties</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>You can set database properties using the <code class="classname">DatabaseConfig</code>
|
||||
class. For each of the properties that you can set, there is a
|
||||
corresponding getter method. Also, you can always retrieve the
|
||||
<code class="classname">DatabaseConfig</code> object used by your database using
|
||||
the <code class="methodname">Database.getConfig()</code> method.</p>
|
||||
<p>The database properties that you can set are:</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
<code class="methodname">DatabaseConfig.setAllowCreate()</code>
|
||||
</p>
|
||||
<p>If <code class="literal">true</code>, the database is created when it is
|
||||
opened. If false, the database open fails if the database does not
|
||||
exist. This property has no meaning if the database currently exists.
|
||||
Default is <code class="literal">false</code>.</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="methodname">DatabaseConfig.setBtreeComparator()</code>
|
||||
</p>
|
||||
<p>Sets the class that is used to compare the keys found on two
|
||||
database records. This class is used to determine the sort order for
|
||||
two records in the database. By default, byte for byte comparison is
|
||||
used.
|
||||
For more information, see
|
||||
<span><a class="xref" href="comparator.html" title="Using Comparators">Using Comparators</a>.</span>
|
||||
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="methodname">DatabaseConfig.setDuplicateComparator()</code>
|
||||
</p>
|
||||
<p>
|
||||
Sets the class that is used to compare two duplicate records in
|
||||
the database. For more information, see
|
||||
<span><a class="xref" href="comparator.html" title="Using Comparators">Using Comparators</a>.</span>
|
||||
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="methodname">DatabaseConfig.setSortedDuplicates()</code>
|
||||
</p>
|
||||
<p>If <code class="literal">true</code>, duplicate records are allowed in the
|
||||
database. If this value is <code class="literal">false</code>, then putting a duplicate record into the database
|
||||
results in an error return from the put call.
|
||||
Note that this property can be set only at database creation time. Default is <code class="literal">false</code>.
|
||||
</p>
|
||||
<p>
|
||||
Note that your database must not support duplicates if it is to be associated with one or more
|
||||
secondary indices. Secondaries are described in <a class="xref" href="indexes.html" title="Chapter 10. Secondary Databases">Secondary Databases</a>.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="methodname">DatabaseConfig.setExclusiveCreate()</code>
|
||||
</p>
|
||||
<p>If <code class="literal">true</code>, the database open fails if the
|
||||
database currently exists. That is, the open must result in the
|
||||
creation of a new database. Default is <code class="literal">false</code>.</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="methodname">DatabaseConfig.setReadOnly()</code>
|
||||
</p>
|
||||
<p>If true, the database is opened for read activities only.
|
||||
Default is <code class="literal">false</code>.</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="methodname">DatabaseConfig.setTransactional()</code>
|
||||
</p>
|
||||
<p>If true, the database supports transactions.
|
||||
Default is <code class="literal">false</code>. Note that a database cannot support
|
||||
transactions if the environment is non-transactional.</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<p>For example:</p>
|
||||
<a id="je_db3"></a>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.je.DatabaseException;
|
||||
import com.sleepycat.je.Database;
|
||||
import com.sleepycat.je.DatabaseConfig;
|
||||
|
||||
...
|
||||
// Environment open omitted for brevity
|
||||
...
|
||||
|
||||
Database myDatabase = null;
|
||||
try {
|
||||
DatabaseConfig dbConfig = new DatabaseConfig();
|
||||
dbConfig.setAllowCreate(true);
|
||||
dbConfig.setSortedDuplicates(true);
|
||||
myDatabase =
|
||||
myDbEnv.openDatabase(null,
|
||||
"sampleDatabase",
|
||||
dbConfig);
|
||||
} catch (DatabaseException dbe) {
|
||||
// Exception handling goes here.
|
||||
}</pre>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="databases.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="databases.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="DBAdmin.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Chapter 7. Databases </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Administrative Methods</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
693
docs/GettingStartedGuide/dbtUsage.html
Normal file
693
docs/GettingStartedGuide/dbtUsage.html
Normal file
|
|
@ -0,0 +1,693 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Database Record Example</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="DBEntry.html" title="Chapter 8. Database Records" />
|
||||
<link rel="prev" href="comparator.html" title="Using Comparators" />
|
||||
<link rel="next" href="Cursors.html" title="Chapter 9. Using Cursors" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Database Record Example</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="comparator.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 8. Database Records</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="Cursors.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="dbtUsage"></a>Database Record Example</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>In <a class="xref" href="dbUsage.html" title="Database Example">Database Example</a>, we created
|
||||
<code class="classname">MyDbEnv</code>, a class that manages
|
||||
<code class="classname">DatabaseEnvironment</code> and <code class="classname">Database</code>
|
||||
opens and closes. We will now write an application that takes advantage of
|
||||
this class to open databases, put a series of records in them, and then
|
||||
close the databases and environment.</p>
|
||||
<p>Remember that all of the classes and programs presented here can be
|
||||
found in the following directory:
|
||||
</p>
|
||||
<pre class="programlisting"><span class="emphasis"><em>JE_HOME</em></span>/examples/je/gettingStarted</pre>
|
||||
<p>
|
||||
where <code class="literal"><span class="emphasis"><em>JE_HOME</em></span></code> is the location where you
|
||||
placed your JE distribution.
|
||||
</p>
|
||||
<p>Note that in this example, we are going to save two types of
|
||||
information. First there are a series of inventory records that identify
|
||||
information about some food items (fruits, vegetables, and desserts).
|
||||
These records identify particulars about each item such as the vendor that
|
||||
the item can be obtained from, how much the vendor has in stock, the price
|
||||
per unit, and so forth.</p>
|
||||
<p>
|
||||
We also want to manage vendor contact information, such as the
|
||||
vendor's address and phone number, the sales representative's name
|
||||
and his phone number, and so forth.
|
||||
</p>
|
||||
<div class="example">
|
||||
<a id="inventory"></a>
|
||||
<p class="title">
|
||||
<b>Example 8.1 Inventory.java</b>
|
||||
</p>
|
||||
<div class="example-contents">
|
||||
<p>
|
||||
All Inventory data is encapsulated in an instance of the following
|
||||
class. Note that because this class is not serializable, we need a
|
||||
custom tuple binding in order to place it on a <code class="classname">DatabaseEntry</code>
|
||||
object. Because the <code class="classname">TupleInput</code> and
|
||||
<code class="classname">TupleOutput</code> classes used by custom tuple bindings
|
||||
support Java numerical types and not Java numerical classes, we use
|
||||
<code class="literal">int</code> and <code class="literal">float</code> here instead of the
|
||||
corresponding <code class="classname">Integer</code> and <code class="classname">Float</code>
|
||||
classes.
|
||||
|
||||
</p>
|
||||
<a id="je_dbt16"></a>
|
||||
<pre class="programlisting">// File Inventory.java
|
||||
package je.gettingStarted;
|
||||
|
||||
public class Inventory {
|
||||
|
||||
private String sku;
|
||||
private String itemName;
|
||||
private String category;
|
||||
private String vendor;
|
||||
private int vendorInventory;
|
||||
private float vendorPrice;
|
||||
|
||||
public void setSku(String data) {
|
||||
sku = data;
|
||||
}
|
||||
|
||||
public void setItemName(String data) {
|
||||
itemName = data;
|
||||
}
|
||||
|
||||
public void setCategory(String data) {
|
||||
category = data;
|
||||
}
|
||||
|
||||
public void setVendorInventory(int data) {
|
||||
vendorInventory = data;
|
||||
}
|
||||
|
||||
public void setVendor(String data) {
|
||||
vendor = data;
|
||||
}
|
||||
|
||||
public void setVendorPrice(float data) {
|
||||
vendorPrice = data;
|
||||
}
|
||||
|
||||
public String getSku() { return sku; }
|
||||
public String getItemName() { return itemName; }
|
||||
public String getCategory() { return category; }
|
||||
public int getVendorInventory() { return vendorInventory; }
|
||||
public String getVendor() { return vendor; }
|
||||
public float getVendorPrice() { return vendorPrice; }
|
||||
|
||||
} </pre>
|
||||
</div>
|
||||
</div>
|
||||
<br class="example-break" />
|
||||
<div class="example">
|
||||
<a id="vendor"></a>
|
||||
<p class="title">
|
||||
<b>Example 8.2 Vendor.java</b>
|
||||
</p>
|
||||
<div class="example-contents">
|
||||
<p>
|
||||
The data for vendor records are stored in instances of the following
|
||||
class. Notice that we are using serialization with this class simply
|
||||
to demonstrate serializing a class instance.
|
||||
</p>
|
||||
<a id="je_dbt17"></a>
|
||||
<pre class="programlisting">// File Vendor.java
|
||||
package je.gettingStarted;
|
||||
|
||||
import java.io.Serializable;
|
||||
|
||||
public class Vendor implements Serializable {
|
||||
|
||||
private String repName;
|
||||
private String address;
|
||||
private String city;
|
||||
private String state;
|
||||
private String zipcode;
|
||||
private String bizPhoneNumber;
|
||||
private String repPhoneNumber;
|
||||
private String vendor;
|
||||
|
||||
public void setRepName(String data) {
|
||||
repName = data;
|
||||
}
|
||||
|
||||
public void setAddress(String data) {
|
||||
address = data;
|
||||
}
|
||||
|
||||
public void setCity(String data) {
|
||||
city = data;
|
||||
}
|
||||
|
||||
public void setState(String data) {
|
||||
state = data;
|
||||
}
|
||||
|
||||
public void setZipcode(String data) {
|
||||
zipcode = data;
|
||||
}
|
||||
|
||||
public void setBusinessPhoneNumber(String data) {
|
||||
bizPhoneNumber = data;
|
||||
}
|
||||
|
||||
public void setRepPhoneNumber(String data) {
|
||||
repPhoneNumber = data;
|
||||
}
|
||||
|
||||
public void setVendorName(String data) {
|
||||
vendor = data;
|
||||
}
|
||||
|
||||
...
|
||||
// Corresponding getter methods omitted for brevity.
|
||||
// See examples/je/gettingStarted/Vendor.java
|
||||
// for a complete implementation of this class.
|
||||
|
||||
} </pre>
|
||||
</div>
|
||||
</div>
|
||||
<br class="example-break" />
|
||||
<p>
|
||||
Because we will not be using serialization to convert our
|
||||
<code class="classname">Inventory</code> objects to a <code class="classname">DatabaseEntry</code>
|
||||
object, we need a custom tuple binding:
|
||||
</p>
|
||||
<div class="example">
|
||||
<a id="InventoryBinding"></a>
|
||||
<p class="title">
|
||||
<b>Example 8.3 InventoryBinding.java</b>
|
||||
</p>
|
||||
<div class="example-contents">
|
||||
<a id="je_dbt18"></a>
|
||||
<pre class="programlisting">// File InventoryBinding.java
|
||||
package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.bind.tuple.TupleBinding;
|
||||
import com.sleepycat.bind.tuple.TupleInput;
|
||||
import com.sleepycat.bind.tuple.TupleOutput;
|
||||
|
||||
public class InventoryBinding extends TupleBinding {
|
||||
|
||||
// Implement this abstract method. Used to convert
|
||||
// a DatabaseEntry to an Inventory object.
|
||||
public Object entryToObject(TupleInput ti) {
|
||||
|
||||
String sku = ti.readString();
|
||||
String itemName = ti.readString();
|
||||
String category = ti.readString();
|
||||
String vendor = ti.readString();
|
||||
int vendorInventory = ti.readInt();
|
||||
float vendorPrice = ti.readFloat();
|
||||
|
||||
Inventory inventory = new Inventory();
|
||||
inventory.setSku(sku);
|
||||
inventory.setItemName(itemName);
|
||||
inventory.setCategory(category);
|
||||
inventory.setVendor(vendor);
|
||||
inventory.setVendorInventory(vendorInventory);
|
||||
inventory.setVendorPrice(vendorPrice);
|
||||
|
||||
return inventory;
|
||||
}
|
||||
|
||||
// Implement this abstract method. Used to convert a
|
||||
// Inventory object to a DatabaseEntry object.
|
||||
public void objectToEntry(Object object, TupleOutput to) {
|
||||
|
||||
Inventory inventory = (Inventory)object;
|
||||
|
||||
to.writeString(inventory.getSku());
|
||||
to.writeString(inventory.getItemName());
|
||||
to.writeString(inventory.getCategory());
|
||||
to.writeString(inventory.getVendor());
|
||||
to.writeInt(inventory.getVendorInventory());
|
||||
to.writeFloat(inventory.getVendorPrice());
|
||||
}
|
||||
} </pre>
|
||||
</div>
|
||||
</div>
|
||||
<br class="example-break" />
|
||||
<p>In order to store the data identified above, we write the
|
||||
<code class="classname">ExampleDatabasePut</code> application. This application
|
||||
loads the inventory and vendor databases for you.</p>
|
||||
<p>Inventory information is stored in a <code class="classname">Database</code>
|
||||
dedicated for that purpose. The key for each such record is a product SKU.
|
||||
The inventory data stored in this database are objects of the
|
||||
<code class="classname">Inventory</code> class (see <a class="xref" href="dbtUsage.html#inventory" title="Example 8.1 Inventory.java">Inventory.java</a> for more information).
|
||||
<code class="classname">ExampleDatabasePut</code> loads the inventory database
|
||||
as follows:</p>
|
||||
<div class="orderedlist">
|
||||
<ol type="1">
|
||||
<li>
|
||||
<p>Reads the inventory data from a flat text file prepared in
|
||||
advance for this purpose.</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>Uses <code class="classname">java.lang.String</code> to create a key
|
||||
based on the item's SKU.</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>Uses an <code class="classname">Inventory</code> class instance for the
|
||||
record data. This object is stored on a <code class="classname">DatabaseEntry</code>
|
||||
object using <code class="classname">InventoryBinding</code>, a custom tuple
|
||||
binding that we implemented above.</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>Saves each record to the inventory database.</p>
|
||||
</li>
|
||||
</ol>
|
||||
</div>
|
||||
<p>Vendor information is also stored in a <code class="classname">Database</code>
|
||||
dedicated for that purpose. The vendor data stored in this database are objects of the
|
||||
<code class="classname">Vendor</code> class (see <a class="xref" href="dbtUsage.html#vendor" title="Example 8.2 Vendor.java">Vendor.java</a> for more information). To load this
|
||||
<code class="classname">Database</code>, <code class="classname">ExampleDatabasePut</code>
|
||||
does the following:</p>
|
||||
<div class="orderedlist">
|
||||
<ol type="1">
|
||||
<li>
|
||||
<p>Reads the vendor data from a flat text file prepared in advance
|
||||
for this purpose.</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>Uses the vendor's name as the record's key.</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>Uses a <code class="classname">Vendor</code> class instance for the
|
||||
record data. This object is stored on a <code class="classname">DatabaseEntry</code>
|
||||
object using <code class="classname">com.sleepycat.bind.serial.SerialBinding</code>.</p>
|
||||
</li>
|
||||
</ol>
|
||||
</div>
|
||||
<div class="example">
|
||||
<a id="dbenvStoredClass"></a>
|
||||
<p class="title">
|
||||
<b>Example 8.4 Stored Class Catalog Management with MyDbEnv</b>
|
||||
</p>
|
||||
<div class="example-contents">
|
||||
<p>
|
||||
Before we can write <code class="classname">ExampleDatabasePut</code>, we need to update
|
||||
<code class="filename">MyDbEnv.java</code> to support the class catalogs that we need for this application.
|
||||
</p>
|
||||
<p>
|
||||
To do this, we start by importing an additional class to support stored class catalogs:
|
||||
</p>
|
||||
<a id="je_dbt19"></a>
|
||||
<pre class="programlisting">// File MyDbEnv.java
|
||||
package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.je.Database;
|
||||
import com.sleepycat.je.DatabaseConfig;
|
||||
import com.sleepycat.je.DatabaseException;
|
||||
import com.sleepycat.je.EnvironmentConfig;
|
||||
import com.sleepycat.je.Environment;
|
||||
|
||||
import java.io.File;
|
||||
|
||||
<strong class="userinput"><code>import com.sleepycat.bind.serial.StoredClassCatalog;</code></strong> </pre>
|
||||
<p>
|
||||
We also need to add two additional private data members to this class. One supports the database used for the class
|
||||
catalog, and the other is used as a handle for the class catalog itself.
|
||||
</p>
|
||||
<a id="je_dbt20"></a>
|
||||
<pre class="programlisting">public class MyDbEnv {
|
||||
|
||||
private Environment myEnv;
|
||||
private Database vendorDb;
|
||||
private Database inventoryDb;
|
||||
<strong class="userinput"><code>private Database classCatalogDb;
|
||||
|
||||
// Needed for object serialization
|
||||
private StoredClassCatalog classCatalog;</code></strong>
|
||||
|
||||
public MyDbEnv() {} </pre>
|
||||
<p>
|
||||
Next we need to update the <code class="methodname">MyDbEnv.setup()</code> method to open the class catalog database and
|
||||
create the class catalog.
|
||||
</p>
|
||||
<a id="je_dbt21"></a>
|
||||
<pre class="programlisting"> public void setup(File envHome, boolean readOnly)
|
||||
throws DatabaseException {
|
||||
|
||||
...
|
||||
// Database and environment configuration omitted for brevity
|
||||
...
|
||||
|
||||
// Instantiate the Environment. This opens it and also possibly
|
||||
// creates it.
|
||||
myEnv = new Environment(envHome, myEnvConfig);
|
||||
|
||||
// Now create and open our databases.
|
||||
vendorDb = myEnv.openDatabase(null, "VendorDB", myDbConfig);
|
||||
|
||||
inventoryDb = myEnv.openDatabase(null, "InventoryDB", myDbConfig);
|
||||
|
||||
<strong class="userinput"><code>// Open the class catalog db. This is used to
|
||||
// optimize class serialization.
|
||||
classCatalogDb =
|
||||
myEnv.openDatabase(null,
|
||||
"ClassCatalogDB",
|
||||
myDbConfig);
|
||||
|
||||
// Create our class catalog
|
||||
classCatalog = new StoredClassCatalog(classCatalogDb);</code></strong>
|
||||
} </pre>
|
||||
<p>
|
||||
Next we need a getter method to return the class catalog. Note that we do not provide a getter for
|
||||
the catalog database itself – our application has no need for that.
|
||||
</p>
|
||||
<a id="je_dbt22"></a>
|
||||
<pre class="programlisting">// Getter methods
|
||||
public Environment getEnvironment() {
|
||||
return myEnv;
|
||||
}
|
||||
|
||||
public Database getVendorDB() {
|
||||
return vendorDb;
|
||||
}
|
||||
|
||||
public Database getInventoryDB() {
|
||||
return inventoryDb;
|
||||
}
|
||||
|
||||
<strong class="userinput"><code>public StoredClassCatalog getClassCatalog() {
|
||||
return classCatalog;
|
||||
}</code></strong> </pre>
|
||||
<p>
|
||||
Finally, we need to update the <code class="methodname">MyDbEnv.close()</code> method to close the
|
||||
class catalog database.
|
||||
</p>
|
||||
<a id="je_dbt23"></a>
|
||||
<pre class="programlisting"> // Close the environment
|
||||
public void close() {
|
||||
if (myEnv != null) {
|
||||
try {
|
||||
vendorDb.close();
|
||||
inventoryDb.close();
|
||||
<strong class="userinput"><code>classCatalogDb.close()</code></strong>
|
||||
myEnv.close();
|
||||
} catch(DatabaseException dbe) {
|
||||
System.err.println("Error closing MyDbEnv: " +
|
||||
dbe.toString());
|
||||
System.exit(-1);
|
||||
}
|
||||
}
|
||||
}
|
||||
}</pre>
|
||||
</div>
|
||||
</div>
|
||||
<br class="example-break" />
|
||||
<p>
|
||||
So far we have identified the data that we want to store in our
|
||||
databases and how we will convert that data in and out of
|
||||
<code class="classname">DatabaseEntry</code> objects for database storage. We
|
||||
have also updated <code class="classname">MyDbEnv</code> to manage our databases
|
||||
for us. Now we write <code class="classname">ExampleDatabasePut</code> to
|
||||
actually put the inventory and vendor data into their respective
|
||||
databases. Because of the work that we have done so far, this
|
||||
application is actually fairly simple to write.
|
||||
</p>
|
||||
<div class="example">
|
||||
<a id="EDP"></a>
|
||||
<p class="title">
|
||||
<b>Example 8.5 ExampleDatabasePut.java</b>
|
||||
</p>
|
||||
<div class="example-contents">
|
||||
<p>First we need the usual series of import statements:</p>
|
||||
<a id="je_dbt24"></a>
|
||||
<pre class="programlisting">//File ExampleDatabasePut.java
|
||||
package je.gettingStarted;
|
||||
|
||||
// Bind classes used to move class objects in an out of byte arrays.
|
||||
import com.sleepycat.bind.EntryBinding;
|
||||
import com.sleepycat.bind.serial.SerialBinding;
|
||||
import com.sleepycat.bind.tuple.TupleBinding;
|
||||
|
||||
// Standard JE database imports
|
||||
import com.sleepycat.je.DatabaseEntry;
|
||||
import com.sleepycat.je.DatabaseException;
|
||||
|
||||
// Most of this is used for loading data from a text file for storage
|
||||
// in the databases.
|
||||
import java.io.File;
|
||||
import java.io.FileInputStream;
|
||||
import java.io.BufferedReader;
|
||||
import java.io.InputStreamReader;
|
||||
import java.io.FileNotFoundException;
|
||||
import java.io.IOException;
|
||||
import java.util.ArrayList;
|
||||
import java.util.List;</pre>
|
||||
<p>Next comes the class declaration and the private data members that
|
||||
we need for this class. Most of these are setting up default values for
|
||||
the program.</p>
|
||||
<p>Note that two <code class="classname">DatabaseEntry</code> objects are
|
||||
instantiated here. We will reuse these for every database operation that
|
||||
this program performs. Also a <code class="classname">MyDbEnv</code> object is
|
||||
instantiated here. We can do this because its constructor never throws
|
||||
an exception. See <a class="xref" href="dbtUsage.html#dbenvStoredClass" title="Example 8.4 Stored Class Catalog Management with MyDbEnv">Stored Class Catalog Management with MyDbEnv</a> for
|
||||
its implementation details.</p>
|
||||
<p>Finally, the <code class="filename">inventory.txt</code> and
|
||||
<code class="filename">vendors.txt</code> file can be found in the GettingStarted
|
||||
examples directory along with the classes described in this extended
|
||||
example.</p>
|
||||
<a id="je_dbt25"></a>
|
||||
<pre class="programlisting">public class ExampleDatabasePut {
|
||||
|
||||
private static File myDbEnvPath = new File("/tmp/JEDB");
|
||||
private static File inventoryFile = new File("./inventory.txt");
|
||||
private static File vendorsFile = new File("./vendors.txt");
|
||||
|
||||
// DatabaseEntries used for loading records
|
||||
private static DatabaseEntry theKey = new DatabaseEntry();
|
||||
private static DatabaseEntry theData = new DatabaseEntry();
|
||||
|
||||
// Encapsulates the environment and databases.
|
||||
private static MyDbEnv myDbEnv = new MyDbEnv();</pre>
|
||||
<p>
|
||||
Next comes the <code class="methodname">usage()</code> and
|
||||
<code class="methodname">main()</code> methods. Notice the exception handling
|
||||
in the <code class="methodname">main()</code> method. This is the only place in the application where we
|
||||
catch exceptions. For this reason, we must catch
|
||||
<code class="classname">DatabaseException</code> which is thrown by the
|
||||
<code class="literal">com.sleepycat.je.*</code> classes.
|
||||
</p>
|
||||
<p>Also notice the call to <code class="methodname">MyDbEnv.close()</code>
|
||||
in the <code class="literal">finally</code> block. This is the only place in the
|
||||
application where <code class="methodname">MyDbEnv.close()</code> is called.
|
||||
<code class="methodname">MyDbEnv.close()</code> is responsible for closing the
|
||||
<code class="classname">Environment</code> and all open <code class="classname">Database</code>
|
||||
handles for you.</p>
|
||||
<a id="je_dbt26"></a>
|
||||
<pre class="programlisting"> private static void usage() {
|
||||
System.out.println("ExampleDatabasePut [-h <env directory>]");
|
||||
System.out.println(" [-s <selections file>]");
|
||||
System.out.println(" [-v <vendors file>]");
|
||||
System.exit(-1);
|
||||
}
|
||||
|
||||
public static void main(String args[]) {
|
||||
ExampleDatabasePut edp = new ExampleDatabasePut();
|
||||
try {
|
||||
edp.run(args);
|
||||
} catch (DatabaseException dbe) {
|
||||
System.err.println("ExampleDatabasePut: " + dbe.toString());
|
||||
dbe.printStackTrace();
|
||||
} catch (Exception e) {
|
||||
System.err.println("Exception: " + e.toString());
|
||||
e.printStackTrace();
|
||||
} finally {
|
||||
myDbEnv.close();
|
||||
}
|
||||
System.out.println("All done.");
|
||||
} </pre>
|
||||
<p>Next we write the <code class="methodname">ExampleDatabasePut.run()</code>
|
||||
method. This method is responsible for initializing all objects.
|
||||
Because our environment and databases are all opened using the
|
||||
<code class="methodname">MyDbEnv.setup()</code> method, <code class="methodname">ExampleDatabasePut.run()</code>
|
||||
method is only responsible for calling <code class="methodname">MyDbEnv.setup()</code> and then calling
|
||||
the <code class="classname">ExampleDatabasePut</code> methods that actually load the databases.
|
||||
</p>
|
||||
<a id="je_dbt27"></a>
|
||||
<pre class="programlisting"> private void run(String args[]) throws DatabaseException {
|
||||
// Parse the arguments list
|
||||
parseArgs(args);
|
||||
|
||||
myDbEnv.setup(myDbEnvPath, // path to the environment home
|
||||
false); // is this environment read-only?
|
||||
|
||||
System.out.println("loading vendors db.");
|
||||
loadVendorsDb();
|
||||
System.out.println("loading inventory db.");
|
||||
loadInventoryDb();
|
||||
} </pre>
|
||||
<p>This next method loads the vendor database. This method
|
||||
uses serialization to convert the <code class="classname">Vendor</code> object
|
||||
to a <code class="classname">DatabaseEntry</code> object.</p>
|
||||
<a id="je_dbt28"></a>
|
||||
<pre class="programlisting"> private void loadVendorsDb()
|
||||
throws DatabaseException {
|
||||
|
||||
// loadFile opens a flat-text file that contains our data
|
||||
// and loads it into a list for us to work with. The integer
|
||||
// parameter represents the number of fields expected in the
|
||||
// file.
|
||||
List<String[]> vendors = loadFile(vendorsFile, 8);
|
||||
|
||||
// Now load the data into the database. The vendor's name is the
|
||||
// key, and the data is a Vendor class object.
|
||||
|
||||
// Need a serial binding for the data
|
||||
EntryBinding dataBinding =
|
||||
new SerialBinding(myDbEnv.getClassCatalog(), Vendor.class);
|
||||
|
||||
for (int i = 0; i < vendors.size(); i++) {
|
||||
String[] sArray = vendors.get(i);
|
||||
Vendor theVendor = new Vendor();
|
||||
theVendor.setVendorName(sArray[0]);
|
||||
theVendor.setAddress(sArray[1]);
|
||||
theVendor.setCity(sArray[2]);
|
||||
theVendor.setState(sArray[3]);
|
||||
theVendor.setZipcode(sArray[4]);
|
||||
theVendor.setBusinessPhoneNumber(sArray[5]);
|
||||
theVendor.setRepName(sArray[6]);
|
||||
theVendor.setRepPhoneNumber(sArray[7]);
|
||||
|
||||
// The key is the vendor's name.
|
||||
// ASSUMES THE VENDOR'S NAME IS UNIQUE!
|
||||
String vendorName = theVendor.getVendorName();
|
||||
try {
|
||||
theKey = new DatabaseEntry(vendorName.getBytes("UTF-8"));
|
||||
} catch (IOException willNeverOccur) {}
|
||||
|
||||
// Convert the Vendor object to a DatabaseEntry object
|
||||
// using our SerialBinding
|
||||
dataBinding.objectToEntry(theVendor, theData);
|
||||
|
||||
// Put it in the database. These puts are transactionally
|
||||
// protected (we're using autocommit).
|
||||
myDbEnv.getVendorDB().put(null, theKey, theData);
|
||||
}
|
||||
} </pre>
|
||||
<p>Now load the inventory database. This method uses our
|
||||
custom tuple binding (see <a class="xref" href="dbtUsage.html#InventoryBinding" title="Example 8.3 InventoryBinding.java">InventoryBinding.java</a>) to convert the <code class="classname">Inventory</code>
|
||||
object to a <code class="classname">DatabaseEntry</code> object.</p>
|
||||
<a id="je_dbt29"></a>
|
||||
<pre class="programlisting"> private void loadInventoryDb()
|
||||
throws DatabaseException {
|
||||
|
||||
// loadFile opens a flat-text file that contains our data
|
||||
// and loads it into a list for us to work with. The integer
|
||||
// parameter represents the number of fields expected in the
|
||||
// file.
|
||||
List<String[]> inventoryArray = loadFile(inventoryFile, 6);
|
||||
|
||||
// Now load the data into the database. The item's sku is the
|
||||
// key, and the data is an Inventory class object.
|
||||
|
||||
// Need a tuple binding for the Inventory class.
|
||||
TupleBinding inventoryBinding = new InventoryBinding();
|
||||
|
||||
for (int i = 0; i < inventoryArray.size(); i++) {
|
||||
String[] sArray = inventoryArray.get(i);
|
||||
String sku = sArray[1];
|
||||
try {
|
||||
theKey = new DatabaseEntry(sku.getBytes("UTF-8"));
|
||||
} catch (IOException willNeverOccur) {}
|
||||
|
||||
Inventory theInventory = new Inventory();
|
||||
theInventory.setItemName(sArray[0]);
|
||||
theInventory.setSku(sArray[1]);
|
||||
theInventory.setVendorPrice(
|
||||
(new Float(sArray[2])).floatValue());
|
||||
theInventory.setVendorInventory(
|
||||
(new Integer(sArray[3])).intValue());
|
||||
theInventory.setCategory(sArray[4]);
|
||||
theInventory.setVendor(sArray[5]);
|
||||
|
||||
// Place the Vendor object on the DatabaseEntry object using
|
||||
// our the tuple binding we implemented in
|
||||
// InventoryBinding.java
|
||||
inventoryBinding.objectToEntry(theInventory, theData);
|
||||
|
||||
// Put it in the database.
|
||||
myDbEnv.getInventoryDB().put(null, theKey, theData);
|
||||
|
||||
}
|
||||
}</pre>
|
||||
<p>The remainder of this application provides utility methods to
|
||||
read a flat text file into an array of strings and parse the
|
||||
command line options. From the perspective of this document, these
|
||||
things are relatively uninteresting. You can see how they are
|
||||
implemented by looking at:
|
||||
</p>
|
||||
<pre class="programlisting"><span class="emphasis"><em>JE_HOME</em></span>/examples/je/gettingStarted/ExampleDataPut.java </pre>
|
||||
<p>
|
||||
where <code class="literal"><span class="emphasis"><em>JE_HOME</em></span></code> is the location where you
|
||||
placed your JE distribution.
|
||||
</p>
|
||||
<a id="je_dbt30"></a>
|
||||
<pre class="programlisting"> private static void parseArgs(String args[]) {
|
||||
// Implementation omitted for brevity.
|
||||
}
|
||||
|
||||
private List loadFile(File theFile, int numFields) {
|
||||
List<String[]> records = new ArrayList<String[]>();
|
||||
// Implementation omitted for brevity.
|
||||
return records;
|
||||
}
|
||||
|
||||
protected ExampleDatabasePut() {}
|
||||
} </pre>
|
||||
</div>
|
||||
</div>
|
||||
<br class="example-break" />
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="comparator.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="DBEntry.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="Cursors.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Using Comparators </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Chapter 9. Using Cursors</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
124
docs/GettingStartedGuide/diskthreshold.html
Normal file
124
docs/GettingStartedGuide/diskthreshold.html
Normal file
|
|
@ -0,0 +1,124 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Setting Disk Thresholds</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="administration.html" title="Chapter 12. Administering Berkeley DB Java Edition Applications" />
|
||||
<link rel="prev" href="cachesize.html" title="Sizing the Cache" />
|
||||
<link rel="next" href="commandlinetools.html" title="The Command Line Tools" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Setting Disk Thresholds</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="cachesize.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 12. Administering Berkeley DB Java Edition Applications</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="commandlinetools.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="diskthreshold"></a>Setting Disk Thresholds</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
You can control the maximum amount of disk space that JE can use by setting two different
|
||||
threshold values. If JE exceeds either of these threshold values, writes will no longer
|
||||
be allowed to the database. Instead, when a write is attempted, <a class="ulink" href="../java/com/sleepycat/je/DiskLimitException.html" target="_top">DiskLimitException</a> is thrown.
|
||||
The thresholds you can set are:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
<a class="ulink" href="../java/com/sleepycat/je/EnvironmentConfig.html#MAX_DISK" target="_top">EnvironmentConfig.MAX_DISK</a>
|
||||
</p>
|
||||
<p>
|
||||
Specifies an upper limit on the total number of bytes that can be used for data storage.
|
||||
By default, this property is set to <code class="literal">0</code>, which means no upper
|
||||
limit is enforced. Instead, the value set for <a class="ulink" href="../java/com/sleepycat/je/EnvironmentConfig.html#FREE_DISK" target="_top">EnvironmentConfig.FREE_DISK</a> will control your
|
||||
how much disk space your database is allowed to consume.
|
||||
</p>
|
||||
<p>
|
||||
If multiple JE environments share the same storage volume, Oracle recommends that you
|
||||
set <a class="ulink" href="../java/com/sleepycat/je/EnvironmentConfig.html#MAX_DISK" target="_top">EnvironmentConfig.MAX_DISK</a> to a non-zero value, especially if an external application or service is
|
||||
also consuming space on the disk volume.
|
||||
</p>
|
||||
<p>
|
||||
This value can be managed using the <a class="ulink" href="../java/com/sleepycat/je/EnvironmentMutableConfig.html#setMaxDisk-long-" target="_top">EnvironmentMutableConfig.setMaxDisk()</a> method.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<a class="ulink" href="../java/com/sleepycat/je/EnvironmentConfig.html#FREE_DISK" target="_top">EnvironmentConfig.FREE_DISK</a>
|
||||
</p>
|
||||
<p>
|
||||
Specifies the minimum amount of free space to maintain on the disk volume. The
|
||||
default value is 5 GB, which is large enough to allow manual recovery if the
|
||||
free space threshold is exceeded.
|
||||
</p>
|
||||
<p>
|
||||
If <a class="ulink" href="../java/com/sleepycat/je/EnvironmentConfig.html#MAX_DISK" target="_top">EnvironmentConfig.MAX_DISK</a> is set to <code class="literal">0</code>, then the total amount of
|
||||
space your JE database can consume is:
|
||||
</p>
|
||||
<pre class="programlisting"><disk_size> - <FREE_DISK></pre>
|
||||
<p>
|
||||
So for a 300 GB volume and a free disk size of 5 GB, your database can grow
|
||||
to consume 295 GB.
|
||||
</p>
|
||||
<p>
|
||||
If <a class="ulink" href="../java/com/sleepycat/je/EnvironmentConfig.html#MAX_DISK" target="_top">EnvironmentConfig.MAX_DISK</a> is set to a non-zero value, then the total amount of space
|
||||
your JE database can consume is:
|
||||
</p>
|
||||
<pre class="programlisting"><MAX_DISK> - <FREE_DISK></pre>
|
||||
<p>
|
||||
So for the same 300 GB volume, if max disk is 100 GB and free disk is 5 GB, then
|
||||
your database can consume at most 95 GB.
|
||||
</p>
|
||||
<p>
|
||||
Be aware that the subtraction shown, above, is performed only if <a class="ulink" href="../java/com/sleepycat/je/EnvironmentConfig.html#FREE_DISK" target="_top">EnvironmentConfig.FREE_DISK</a> is explicitly
|
||||
set or <a class="ulink" href="../java/com/sleepycat/je/EnvironmentConfig.html#MAX_DISK" target="_top">EnvironmentConfig.MAX_DISK</a> is greater than 10GB. See the <a class="ulink" href="../java/com/sleepycat/je/EnvironmentConfig.html#FREE_DISK" target="_top">EnvironmentConfig.FREE_DISK</a> Javadoc for more information.
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<p>
|
||||
For usage scenarios, see the <a class="ulink" href="../java/com/sleepycat/je/EnvironmentConfig.html#MAX_DISK" target="_top">EnvironmentConfig.MAX_DISK</a> Javadoc.
|
||||
</p>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="cachesize.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="administration.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="commandlinetools.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Sizing the Cache </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> The Command Line Tools</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
279
docs/GettingStartedGuide/dpl.html
Normal file
279
docs/GettingStartedGuide/dpl.html
Normal file
|
|
@ -0,0 +1,279 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Part I. Programming with the Direct Persistence Layer</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="prev" href="dbenvUsageExample.html" title="Database Environment Management Example" />
|
||||
<link rel="next" href="persist_first.html" title="Chapter 3. Direct Persistence Layer First Steps" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Part I. Programming with the Direct Persistence Layer</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="dbenvUsageExample.html">Prev</a> </td>
|
||||
<th width="60%" align="center"> </th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="persist_first.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="part" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h1 class="title"><a id="dpl"></a>Part I. Programming with the Direct Persistence Layer</h1>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="partintro" lang="en" xml:lang="en">
|
||||
<div></div>
|
||||
<p>
|
||||
This section discusses how to build an
|
||||
application using the DPL. The DPL is ideally
|
||||
suited for those applications that want a
|
||||
mechanism for storing and managing Java class
|
||||
objects in a JE database. Note that the DPL
|
||||
is best suited for applications that work with
|
||||
classes with a relatively static schema.
|
||||
</p>
|
||||
<p>
|
||||
The DPL requires Java 1.5.
|
||||
</p>
|
||||
<p>
|
||||
If you are porting an application
|
||||
from the Berkeley DB API, then you probably want
|
||||
to use the base API instead of the DPL. For
|
||||
information on using the base API, see
|
||||
<a class="xref" href="baseapi.html" title="Part II. Programming with the Base API">Programming with the Base API</a>.
|
||||
</p>
|
||||
<div class="toc">
|
||||
<p>
|
||||
<b>Table of Contents</b>
|
||||
</p>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="chapter">
|
||||
<a href="persist_first.html">3. Direct Persistence Layer First Steps</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="persist_first.html#entitystore">Entity Stores</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="persist_first.html#persist-open">Opening and Closing Environments and Stores</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="persistobject.html">Persistent Objects</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="saveret.html">Saving and Retrieving Data</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="chapter">
|
||||
<a href="persist_index.html">4. Working with Indices</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="persist_index.html#dplindexaccess">Accessing Indexes</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="persist_index.html#primaryindexaccess">Accessing Primary Indices</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="persist_index.html#secondaryindexaccess">Accessing Secondary Indices</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="dplindexcreate.html">Creating Indexes</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="dplindexcreate.html#dplprimaryidxdecl">Declaring Primary Indexes</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="dplindexcreate.html#dplsecondaryidxdecl">Declaring Secondary Indexes</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="dplindexcreate.html#foreignkey">Foreign Key Constraints</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
</dl>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="chapter">
|
||||
<a href="persist_access.html">5. Saving and Retrieving Objects</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="persist_access.html#simpleentity">A Simple Entity Class</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="simpleda.html">SimpleDA.class</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="simpleput.html">Placing Objects in an Entity Store</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="simpleget.html">Retrieving Objects from an Entity Store</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="getmultiple.html">Retrieving Multiple Objects</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="getmultiple.html#dpl_cursor_initialize">Cursor Initialization</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="getmultiple.html#dpl_dups">Working with Duplicate Keys</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="getmultiple.html#dpl_cursor_range">Key Ranges</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="dpl_entityjoin.html">Join Cursors</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="dpl_delete.html">Deleting Entity Objects</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="dpl_replace.html">Replacing Entity Objects</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="chapter">
|
||||
<a href="dpl_example.html">6. A DPL Example</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="dpl_example.html#vendorclass">Vendor.java</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="inventoryclass.html">Inventory.java</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="mydbenv-persist.html">MyDbEnv</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="dataaccessorclass.html">DataAccessor.java</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="dpl_exampledatabaseput.html">ExampleDatabasePut.java</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="dpl_exampleinventoryread.html">ExampleInventoryRead.java</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
</dl>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="dbenvUsageExample.html">Prev</a> </td>
|
||||
<td width="20%" align="center"> </td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="persist_first.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Database Environment Management Example </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Chapter 3. Direct Persistence Layer First Steps</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
114
docs/GettingStartedGuide/dpl_delete.html
Normal file
114
docs/GettingStartedGuide/dpl_delete.html
Normal file
|
|
@ -0,0 +1,114 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Deleting Entity Objects</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="persist_access.html" title="Chapter 5. Saving and Retrieving Objects" />
|
||||
<link rel="prev" href="dpl_entityjoin.html" title="Join Cursors" />
|
||||
<link rel="next" href="dpl_replace.html" title="Replacing Entity Objects" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Deleting Entity Objects</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="dpl_entityjoin.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 5. Saving and Retrieving Objects</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="dpl_replace.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="dpl_delete"></a>Deleting Entity Objects</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
The simplest way to remove an object from your entity store
|
||||
is to delete it by its primary index. For example,
|
||||
using the <code class="classname">SimpleDA</code> class that we
|
||||
created earlier in this document
|
||||
(see <a class="xref" href="simpleda.html" title="SimpleDA.class">SimpleDA.class</a>),
|
||||
you can delete the <code class="classname">SimpleEntityClass</code>
|
||||
object with a primary key of <code class="literal">keyone</code> as
|
||||
follows:
|
||||
</p>
|
||||
<pre class="programlisting">sda.pIdx.delete("keyone");</pre>
|
||||
<p>
|
||||
You can also delete objects by their secondary keys. When
|
||||
you do this, all objects related to the secondary key are
|
||||
deleted, unless the key is a foreign object.
|
||||
</p>
|
||||
<p>
|
||||
For example, the following deletes all
|
||||
<code class="classname">SimpleEntityClass</code> with a secondary
|
||||
key of <code class="literal">skeyone</code>:
|
||||
</p>
|
||||
<pre class="programlisting">sda.sIdx.delete("skeyone");</pre>
|
||||
<p>
|
||||
You can delete any single object by positioning a cursor to
|
||||
that object and then calling the cursor's
|
||||
<code class="methodname">delete()</code> method.
|
||||
</p>
|
||||
<pre class="programlisting">PrimaryIndex<String,SimpleEntityClass> pi =
|
||||
store.getPrimaryIndex(String.class, SimpleEntityClass.class);
|
||||
|
||||
SecondaryIndex<String,String,SimpleEntityClass> si =
|
||||
store.getSecondaryIndex(pi, String.class, "sKey");
|
||||
|
||||
EntityCursor<SimpleEntityClass> sec_cursor =
|
||||
si.subIndex("skeyone").entities();
|
||||
|
||||
try {
|
||||
SimpleEntityClass sec;
|
||||
Iterator<SimpleEntityClass> i = sec_cursor.iterator();
|
||||
while (sec = i.nextDup() != null) {
|
||||
if (sec.getSKey() == "some value") {
|
||||
i.delete();
|
||||
}
|
||||
}
|
||||
// Always make sure the cursor is closed when we are done with it.
|
||||
} finally {
|
||||
sec_cursor.close(); } </pre>
|
||||
<p>
|
||||
Finally, if you are indexing by foreign key, then the
|
||||
results of deleting the key is determined by the foreign
|
||||
key constraint that you have set for the index. See
|
||||
<a class="xref" href="dplindexcreate.html#foreignkey" title="Foreign Key Constraints">Foreign Key Constraints</a>
|
||||
for more information.
|
||||
</p>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="dpl_entityjoin.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="persist_access.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="dpl_replace.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Join Cursors </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Replacing Entity Objects</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
193
docs/GettingStartedGuide/dpl_entityjoin.html
Normal file
193
docs/GettingStartedGuide/dpl_entityjoin.html
Normal file
|
|
@ -0,0 +1,193 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Join Cursors</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="persist_access.html" title="Chapter 5. Saving and Retrieving Objects" />
|
||||
<link rel="prev" href="getmultiple.html" title="Retrieving Multiple Objects" />
|
||||
<link rel="next" href="dpl_delete.html" title="Deleting Entity Objects" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Join Cursors</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="getmultiple.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 5. Saving and Retrieving Objects</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="dpl_delete.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="dpl_entityjoin"></a>Join Cursors</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
If you have two or more secondary indexes set for
|
||||
an entity object, then you can retrieve sets of
|
||||
objects based on the intersection of multiple
|
||||
secondary index values. You do this using an
|
||||
<code class="classname">EntityJoin</code>
|
||||
class.
|
||||
</p>
|
||||
<p>
|
||||
For example, suppose you had an entity class that
|
||||
represented automobiles. In that case, you might
|
||||
be storing information about automobiles such as
|
||||
color, number of doors, fuel mileage,
|
||||
automobile type, number of passengers, make, model, and year,
|
||||
to name just a few.
|
||||
</p>
|
||||
<p>
|
||||
If you created a secondary index based this
|
||||
information, then you could use an
|
||||
<code class="classname">EntityJoin</code> to return
|
||||
all those objects representing cars with, say, two
|
||||
doors, that were built in 2002, and which are green
|
||||
in color.
|
||||
</p>
|
||||
<p>
|
||||
To create a join cursor, you:
|
||||
</p>
|
||||
<div class="orderedlist">
|
||||
<ol type="1">
|
||||
<li>
|
||||
<p>
|
||||
Open the primary index for the
|
||||
entity class on which you want to
|
||||
perform the join.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Open the secondary indexes that you
|
||||
want to use for the join.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Instantiate an
|
||||
<code class="classname">EntityJoin</code>
|
||||
object (you use the primary index
|
||||
to do this).
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Use two or more calls to
|
||||
<code class="methodname">EntityJoin.addCondition()</code>
|
||||
to identify the secondary indexes
|
||||
and their values that you want to use
|
||||
for the equality match.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Call
|
||||
<code class="methodname">EntityJoin.entities()</code>
|
||||
to obtain a cursor that you can use
|
||||
to iterate over the join results.
|
||||
</p>
|
||||
</li>
|
||||
</ol>
|
||||
</div>
|
||||
<p>
|
||||
For example, suppose we had an entity class
|
||||
that included the following features:
|
||||
</p>
|
||||
<pre class="programlisting">package persist.gettingStarted;
|
||||
|
||||
import com.sleepycat.persist.model.Entity;
|
||||
import com.sleepycat.persist.model.PrimaryKey;
|
||||
import static com.sleepycat.persist.model.Relationship.*;
|
||||
import com.sleepycat.persist.model.SecondaryKey;
|
||||
|
||||
@Entity
|
||||
public class Automobiles {
|
||||
|
||||
// Primary key is the vehicle identification number
|
||||
@PrimaryKey
|
||||
private String vin;
|
||||
|
||||
// Secondary key is the vehicle's make
|
||||
@SecondaryKey(relate=MANY_TO_ONE)
|
||||
private String make;
|
||||
|
||||
// Secondary key is the vehicle's color
|
||||
@SecondaryKey(relate=MANY_TO_ONE)
|
||||
private String color;
|
||||
|
||||
...
|
||||
|
||||
public String getVIN() {
|
||||
return vin;
|
||||
}
|
||||
|
||||
public String getMake() {
|
||||
return make;
|
||||
}
|
||||
|
||||
public String getColor() {
|
||||
return color;
|
||||
}
|
||||
|
||||
... </pre>
|
||||
<p>
|
||||
Then we could perform an entity join that searches for all the
|
||||
red automobiles made by Toyota as follows:
|
||||
</p>
|
||||
<pre class="programlisting">
|
||||
PrimaryIndex<String,Automobiles> vin_pidx;
|
||||
SecondaryIndex<String,String,Automobiles> make_sidx;
|
||||
SecondaryIndex<String,String,Automobiles> color_sidx;
|
||||
|
||||
EntityJoin<String,Automobiles> join = new EntityJoin(vin_pidx);
|
||||
join.addCondition(make_sidx,"Toyota");
|
||||
join.addCondition(color_sidx,"Red");
|
||||
|
||||
// Now iterate over the results of the join operation
|
||||
ForwardCursor<Automobiles> join_cursor = join.entities();
|
||||
try {
|
||||
for (Automobiles autoi : join_cursor) {
|
||||
// do something with each object "autoi"
|
||||
}
|
||||
// Always make sure the cursor is closed when we are done with it.
|
||||
} finally {
|
||||
join_cursor.close();
|
||||
} </pre>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="getmultiple.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="persist_access.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="dpl_delete.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Retrieving Multiple Objects </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Deleting Entity Objects</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
275
docs/GettingStartedGuide/dpl_example.html
Normal file
275
docs/GettingStartedGuide/dpl_example.html
Normal file
|
|
@ -0,0 +1,275 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Chapter 6. A DPL Example</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="dpl.html" title="Part I. Programming with the Direct Persistence Layer" />
|
||||
<link rel="prev" href="dpl_replace.html" title="Replacing Entity Objects" />
|
||||
<link rel="next" href="inventoryclass.html" title="Inventory.java" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Chapter 6. A DPL Example</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="dpl_replace.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Part I. Programming with the Direct Persistence Layer</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="inventoryclass.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="chapter" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title"><a id="dpl_example"></a>Chapter 6. A DPL Example</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="toc">
|
||||
<p>
|
||||
<b>Table of Contents</b>
|
||||
</p>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="dpl_example.html#vendorclass">Vendor.java</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="inventoryclass.html">Inventory.java</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="mydbenv-persist.html">MyDbEnv</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="dataaccessorclass.html">DataAccessor.java</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="dpl_exampledatabaseput.html">ExampleDatabasePut.java</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="dpl_exampleinventoryread.html">ExampleInventoryRead.java</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</div>
|
||||
<p>
|
||||
In order to illustrate DPL usage, we provide a
|
||||
complete working example in this chapter. This example
|
||||
reads and writes inventory and vendor information for a
|
||||
mythical business. The application consists of the
|
||||
following classes:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
Several classes used to encapsulate our
|
||||
application's data. See
|
||||
<a class="xref" href="dpl_example.html#vendorclass" title="Vendor.java">Vendor.java</a>
|
||||
and
|
||||
<a class="xref" href="inventoryclass.html" title="Inventory.java">Inventory.java</a>.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
A convenience class used to open and close
|
||||
our environment and entity store. See
|
||||
<a class="xref" href="mydbenv-persist.html" title="MyDbEnv">MyDbEnv</a>.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
A class that loads data into the store. See
|
||||
<a class="xref" href="dpl_exampledatabaseput.html" title="ExampleDatabasePut.java">ExampleDatabasePut.java</a>.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Finally, a class that reads data from the
|
||||
store. See
|
||||
<a class="xref" href="dpl_exampleinventoryread.html" title="ExampleInventoryRead.java">ExampleInventoryRead.java</a>.
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<p>
|
||||
Be aware that this example can be found in your JE distribution in
|
||||
the following location:
|
||||
</p>
|
||||
<p>
|
||||
<span class="emphasis"><em>JE_HOME</em></span>/examples/persist/gettingStarted
|
||||
</p>
|
||||
<p>
|
||||
where <code class="literal"><span class="emphasis"><em>JE_HOME</em></span></code> is the location where you
|
||||
placed your JE distribution.
|
||||
</p>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="vendorclass"></a>Vendor.java</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
The simplest class that our example wants to store contains
|
||||
vendor contact information. This class contains no
|
||||
secondary indices so all we have to do is identify it
|
||||
as an entity class and identify the field in the
|
||||
class used for the primary key.
|
||||
</p>
|
||||
<p>
|
||||
In the following example, we identify the
|
||||
<code class="literal">vendor</code> data member as containing the
|
||||
primary key. This data member is meant to contain a
|
||||
vendor's name. Because of the way we will use our
|
||||
<code class="classname">EntityStore</code>, the value
|
||||
provided for this data member must be unique within
|
||||
the store or runtime errors will result.
|
||||
</p>
|
||||
<p>
|
||||
When used with the DPL, our
|
||||
<code class="classname">Vendor</code> class appears as
|
||||
follows. Notice that the <code class="literal">@Entity</code>
|
||||
annotation appears immediately before the class
|
||||
declaration, and the <code class="literal">@PrimaryKey</code>
|
||||
annotation appears immediately before the
|
||||
<code class="literal">vendor</code> data member declaration.
|
||||
</p>
|
||||
<pre class="programlisting">package persist.gettingStarted;
|
||||
|
||||
import com.sleepycat.persist.model.Entity;
|
||||
import com.sleepycat.persist.model.PrimaryKey;
|
||||
|
||||
@Entity
|
||||
public class Vendor {
|
||||
|
||||
private String address;
|
||||
private String bizPhoneNumber;
|
||||
private String city;
|
||||
private String repName;
|
||||
private String repPhoneNumber;
|
||||
private String state;
|
||||
|
||||
// Primary key is the vendor's name
|
||||
// This assumes that the vendor's name is
|
||||
// unique in the database.
|
||||
@PrimaryKey
|
||||
private String vendor;
|
||||
|
||||
private String zipcode;
|
||||
|
||||
public void setRepName(String data) {
|
||||
repName = data;
|
||||
}
|
||||
|
||||
public void setAddress(String data) {
|
||||
address = data;
|
||||
}
|
||||
|
||||
public void setCity(String data) {
|
||||
city = data;
|
||||
}
|
||||
|
||||
public void setState(String data) {
|
||||
state = data;
|
||||
}
|
||||
|
||||
public void setZipcode(String data) {
|
||||
zipcode = data;
|
||||
}
|
||||
|
||||
public void setBusinessPhoneNumber(String data) {
|
||||
bizPhoneNumber = data;
|
||||
}
|
||||
|
||||
public void setRepPhoneNumber(String data) {
|
||||
repPhoneNumber = data;
|
||||
}
|
||||
|
||||
public void setVendorName(String data) {
|
||||
vendor = data;
|
||||
}
|
||||
|
||||
public String getRepName() {
|
||||
return repName;
|
||||
}
|
||||
|
||||
public String getAddress() {
|
||||
return address;
|
||||
}
|
||||
|
||||
public String getCity() {
|
||||
return city;
|
||||
}
|
||||
|
||||
public String getState() {
|
||||
return state;
|
||||
}
|
||||
|
||||
public String getZipcode() {
|
||||
return zipcode;
|
||||
}
|
||||
|
||||
public String getBusinessPhoneNumber() {
|
||||
return bizPhoneNumber;
|
||||
}
|
||||
|
||||
public String getRepPhoneNumber() {
|
||||
return repPhoneNumber;
|
||||
}
|
||||
} </pre>
|
||||
<p>
|
||||
For this class, the <code class="literal">vendor</code> value is set for an individual
|
||||
<code class="classname">Vendor</code> class object by
|
||||
the <code class="methodname">setVendorName()</code>
|
||||
method. If our example code fails to set this
|
||||
value before storing the object, the data
|
||||
member used to store the primary key is set to a
|
||||
null value. This would result in a runtime
|
||||
error.
|
||||
</p>
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="dpl_replace.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="dpl.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="inventoryclass.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Replacing Entity Objects </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Inventory.java</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
337
docs/GettingStartedGuide/dpl_exampledatabaseput.html
Normal file
337
docs/GettingStartedGuide/dpl_exampledatabaseput.html
Normal file
|
|
@ -0,0 +1,337 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>ExampleDatabasePut.java</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="dpl_example.html" title="Chapter 6. A DPL Example" />
|
||||
<link rel="prev" href="dataaccessorclass.html" title="DataAccessor.java" />
|
||||
<link rel="next" href="dpl_exampleinventoryread.html" title="ExampleInventoryRead.java" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">ExampleDatabasePut.java</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="dataaccessorclass.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 6. A DPL Example</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="dpl_exampleinventoryread.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="dpl_exampledatabaseput"></a>ExampleDatabasePut.java</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
Our example reads inventory and vendor information from
|
||||
flat text files, encapsulates this data in objects of
|
||||
the appropriate type, and then writes each object to an
|
||||
<code class="classname">EntityStore</code>.
|
||||
</p>
|
||||
<p>
|
||||
To begin, we import the Java classes that our example
|
||||
needs. Most of the imports are related to reading the raw
|
||||
data from flat text files and breaking them apart for usage
|
||||
with our data classes. We also import classes from the
|
||||
JE package, but we do not actually import any classes
|
||||
from the DPL. The reason why is because we have
|
||||
placed almost all of our DPL work off into
|
||||
other classes, so there is no need for direct usage of
|
||||
those APIs here.
|
||||
</p>
|
||||
<pre class="programlisting">package persist.gettingStarted;
|
||||
|
||||
import java.io.BufferedReader;
|
||||
import java.io.File;
|
||||
import java.io.FileInputStream;
|
||||
import java.io.FileNotFoundException;
|
||||
import java.io.IOException;
|
||||
import java.io.InputStreamReader;
|
||||
import java.util.ArrayList;
|
||||
import java.util.List;
|
||||
|
||||
import com.sleepycat.je.DatabaseException; </pre>
|
||||
<p>
|
||||
Now we can begin the class itself. Here we set default paths
|
||||
for the on-disk resources that we require (the environment
|
||||
home, and the location of the text files containing our sample
|
||||
data). We also declare <code class="classname">DataAccessor</code>
|
||||
and <code class="classname">MyDbEnv</code> members. We describe these
|
||||
classes and show their implementation in
|
||||
<a class="xref" href="dataaccessorclass.html" title="DataAccessor.java">DataAccessor.java</a>
|
||||
and
|
||||
<a class="xref" href="mydbenv-persist.html" title="MyDbEnv">MyDbEnv</a>.
|
||||
</p>
|
||||
<pre class="programlisting">public class ExampleDatabasePut {
|
||||
|
||||
private static File myDbEnvPath = new File("/tmp/JEDB");
|
||||
private static File inventoryFile = new File("./inventory.txt");
|
||||
private static File vendorsFile = new File("./vendors.txt");
|
||||
|
||||
private DataAccessor da;
|
||||
|
||||
// Encapsulates the environment and data store.
|
||||
private static MyDbEnv myDbEnv = new MyDbEnv();</pre>
|
||||
<p>
|
||||
Next, we provide our <code class="methodname">usage()</code>
|
||||
method. The command line options provided there are necessary
|
||||
only if the default values to the on-disk resources are not
|
||||
sufficient.
|
||||
</p>
|
||||
<pre class="programlisting"> private static void usage() {
|
||||
System.out.println("ExampleDatabasePut [-h <env directory>]");
|
||||
System.out.println(" [-i <inventory file>]");
|
||||
System.out.println(" [-v <vendors file>]");
|
||||
System.exit(-1);
|
||||
} </pre>
|
||||
<p>
|
||||
Our <code class="methodname">main()</code> method is also reasonably
|
||||
self-explanatory. We simply instantiate an
|
||||
<code class="classname">ExampleDatabasePut</code> object there and then
|
||||
call its <code class="methodname">run()</code> method. We also provide a
|
||||
top-level <code class="literal">try</code> block there for any exceptions that might be thrown
|
||||
during runtime.
|
||||
</p>
|
||||
<p>
|
||||
Notice that the <code class="literal">finally</code> statement in the
|
||||
top-level <code class="literal">try</code> block calls
|
||||
<code class="methodname">MyDbEnv.close()</code>. This method closes our
|
||||
<code class="classname">EntityStore</code> and <code class="classname">Environment</code>
|
||||
objects. By placing it here in the <code class="literal">finally</code>
|
||||
statement, we can make sure that our store and environment are
|
||||
always cleanly closed.
|
||||
</p>
|
||||
<pre class="programlisting"> public static void main(String args[]) {
|
||||
ExampleDatabasePut edp = new ExampleDatabasePut();
|
||||
try {
|
||||
edp.run(args);
|
||||
} catch (DatabaseException dbe) {
|
||||
System.err.println("ExampleDatabasePut: " + dbe.toString());
|
||||
dbe.printStackTrace();
|
||||
} catch (Exception e) {
|
||||
System.out.println("Exception: " + e.toString());
|
||||
e.printStackTrace();
|
||||
} finally {
|
||||
myDbEnv.close();
|
||||
}
|
||||
System.out.println("All done.");
|
||||
} </pre>
|
||||
<p>
|
||||
Our <code class="methodname">run()</code> method does four
|
||||
things. It calls <code class="methodname">MyDbEnv.setup()</code>,
|
||||
which opens our <code class="classname">Environment</code> and
|
||||
<code class="classname">EntityStore</code>. It then instantiates a
|
||||
<code class="classname">DataAccessor</code> object, which we will use
|
||||
to write data to the store. It calls
|
||||
<code class="methodname">loadVendorsDb()</code> which loads all of the
|
||||
vendor information. And then it calls
|
||||
<code class="methodname">loadInventoryDb()</code> which loads all of
|
||||
the inventory information.
|
||||
</p>
|
||||
<p>
|
||||
Notice that the <code class="classname">MyDbEnv</code>
|
||||
object is being setup as read-write. This results in the
|
||||
<code class="classname">EntityStore</code> being opened for
|
||||
transactional support.
|
||||
(See <a class="xref" href="mydbenv-persist.html" title="MyDbEnv">MyDbEnv</a>
|
||||
for implementation details.)
|
||||
</p>
|
||||
<pre class="programlisting"> private void run(String args[])
|
||||
throws DatabaseException {
|
||||
// Parse the arguments list
|
||||
parseArgs(args);
|
||||
|
||||
myDbEnv.setup(myDbEnvPath, // Path to the environment home
|
||||
false); // Environment read-only?
|
||||
|
||||
// Open the data accessor. This is used to store
|
||||
// persistent objects.
|
||||
da = new DataAccessor(myDbEnv.getEntityStore());
|
||||
|
||||
System.out.println("loading vendors db....");
|
||||
loadVendorsDb();
|
||||
|
||||
System.out.println("loading inventory db....");
|
||||
loadInventoryDb();
|
||||
} </pre>
|
||||
<p>
|
||||
We can now implement the <code class="methodname">loadVendorsDb()</code>
|
||||
method. This method is responsible for reading the vendor
|
||||
contact information from the appropriate flat-text file,
|
||||
populating <code class="classname">Vendor</code> class objects with the
|
||||
data and then writing it to the <code class="classname">EntityStore</code>.
|
||||
As explained above, each individual object is written with
|
||||
transactional support. However, because a transaction handle is
|
||||
not explicitly used, the write is performed using auto-commit.
|
||||
This happens because the <code class="classname">EntityStore</code>
|
||||
was opened to support transactions.
|
||||
</p>
|
||||
<p>
|
||||
To actually write each class to the
|
||||
<code class="classname">EntityStore</code>, we simply call the
|
||||
<code class="methodname">PrimaryIndex.put()</code> method for the
|
||||
<code class="classname">Vendor</code> entity instance. We obtain this
|
||||
method from our <code class="classname">DataAccessor</code>
|
||||
class.
|
||||
</p>
|
||||
<pre class="programlisting"> private void loadVendorsDb()
|
||||
throws DatabaseException {
|
||||
|
||||
// loadFile opens a flat-text file that contains our data
|
||||
// and loads it into a list for us to work with. The integer
|
||||
// parameter represents the number of fields expected in the
|
||||
// file.
|
||||
List vendors = loadFile(vendorsFile, 8);
|
||||
|
||||
// Now load the data into the store.
|
||||
for (int i = 0; i < vendors.size(); i++) {
|
||||
String[] sArray = (String[])vendors.get(i);
|
||||
Vendor theVendor = new Vendor();
|
||||
theVendor.setVendorName(sArray[0]);
|
||||
theVendor.setAddress(sArray[1]);
|
||||
theVendor.setCity(sArray[2]);
|
||||
theVendor.setState(sArray[3]);
|
||||
theVendor.setZipcode(sArray[4]);
|
||||
theVendor.setBusinessPhoneNumber(sArray[5]);
|
||||
theVendor.setRepName(sArray[6]);
|
||||
theVendor.setRepPhoneNumber(sArray[7]);
|
||||
|
||||
// Put it in the store.
|
||||
da.vendorByName.put(theVendor);
|
||||
}
|
||||
} </pre>
|
||||
<p>
|
||||
Now we can implement our <code class="methodname">loadInventoryDb()</code>
|
||||
method. This does exactly the same thing as the
|
||||
<code class="methodname">loadVendorsDb()</code>
|
||||
method.
|
||||
</p>
|
||||
<pre class="programlisting"> private void loadInventoryDb()
|
||||
throws DatabaseException {
|
||||
|
||||
// loadFile opens a flat-text file that contains our data
|
||||
// and loads it into a list for us to work with. The integer
|
||||
// parameter represents the number of fields expected in the
|
||||
// file.
|
||||
List inventoryArray = loadFile(inventoryFile, 6);
|
||||
|
||||
// Now load the data into the store. The item's sku is the
|
||||
// key, and the data is an Inventory class object.
|
||||
|
||||
for (int i = 0; i < inventoryArray.size(); i++) {
|
||||
String[] sArray = (String[])inventoryArray.get(i);
|
||||
String sku = sArray[1];
|
||||
|
||||
Inventory theInventory = new Inventory();
|
||||
theInventory.setItemName(sArray[0]);
|
||||
theInventory.setSku(sArray[1]);
|
||||
theInventory.setVendorPrice(
|
||||
(new Float(sArray[2])).floatValue());
|
||||
theInventory.setVendorInventory(
|
||||
(new Integer(sArray[3])).intValue());
|
||||
theInventory.setCategory(sArray[4]);
|
||||
theInventory.setVendor(sArray[5]);
|
||||
|
||||
// Put it in the store. Note that this causes our secondary key
|
||||
// to be automatically updated for us.
|
||||
da.inventoryBySku.put(theInventory);
|
||||
}
|
||||
} </pre>
|
||||
<p>
|
||||
The remainder of this example simple parses the command line
|
||||
and loads data from a flat-text file. There is nothing here
|
||||
that is of specific interest to the DPL, but we
|
||||
show this part of the example anyway in the interest of
|
||||
completeness.
|
||||
</p>
|
||||
<pre class="programlisting"> private static void parseArgs(String args[]) {
|
||||
for(int i = 0; i < args.length; ++i) {
|
||||
if (args[i].startsWith("-")) {
|
||||
switch(args[i].charAt(1)) {
|
||||
case 'h':
|
||||
myDbEnvPath = new File(args[++i]);
|
||||
break;
|
||||
case 'i':
|
||||
inventoryFile = new File(args[++i]);
|
||||
break;
|
||||
case 'v':
|
||||
vendorsFile = new File(args[++i]);
|
||||
break;
|
||||
default:
|
||||
usage();
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
private List loadFile(File theFile, int numFields) {
|
||||
List<String[]> records = new ArrayList<String[]>();
|
||||
try {
|
||||
String theLine = null;
|
||||
FileInputStream fis = new FileInputStream(theFile);
|
||||
BufferedReader br =
|
||||
new BufferedReader(new InputStreamReader(fis));
|
||||
while((theLine=br.readLine()) != null) {
|
||||
String[] theLineArray = theLine.split("#");
|
||||
if (theLineArray.length != numFields) {
|
||||
System.out.println("Malformed line found in " +
|
||||
theFile.getPath());
|
||||
System.out.println("Line was: '" + theLine);
|
||||
System.out.println("length found was: " +
|
||||
theLineArray.length);
|
||||
System.exit(-1);
|
||||
}
|
||||
records.add(theLineArray);
|
||||
}
|
||||
// Close the input stream handle
|
||||
fis.close();
|
||||
} catch (FileNotFoundException e) {
|
||||
System.err.println(theFile.getPath() + " does not exist.");
|
||||
e.printStackTrace();
|
||||
usage();
|
||||
} catch (IOException e) {
|
||||
System.err.println("IO Exception: " + e.toString());
|
||||
e.printStackTrace();
|
||||
System.exit(-1);
|
||||
}
|
||||
return records;
|
||||
}
|
||||
|
||||
protected ExampleDatabasePut() {}
|
||||
} </pre>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="dataaccessorclass.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="dpl_example.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="dpl_exampleinventoryread.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">DataAccessor.java </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> ExampleInventoryRead.java</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
271
docs/GettingStartedGuide/dpl_exampleinventoryread.html
Normal file
271
docs/GettingStartedGuide/dpl_exampleinventoryread.html
Normal file
|
|
@ -0,0 +1,271 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>ExampleInventoryRead.java</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="dpl_example.html" title="Chapter 6. A DPL Example" />
|
||||
<link rel="prev" href="dpl_exampledatabaseput.html" title="ExampleDatabasePut.java" />
|
||||
<link rel="next" href="baseapi.html" title="Part II. Programming with the Base API" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">ExampleInventoryRead.java</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="dpl_exampledatabaseput.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 6. A DPL Example</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="baseapi.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="dpl_exampleinventoryread"></a>ExampleInventoryRead.java</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
<code class="classname">ExampleInventoryRead</code>
|
||||
retrieves
|
||||
inventory information from our entity store and
|
||||
displays it. When it displays each inventory item, it
|
||||
also displays the related vendor contact information.
|
||||
</p>
|
||||
<p>
|
||||
<code class="classname">ExampleInventoryRead</code>
|
||||
can do one of two things. If you provide no search
|
||||
criteria, it displays all of the inventory items in the
|
||||
store. If you provide an item name (using the
|
||||
<code class="literal">-s</code> command line switch), then just
|
||||
those inventory items using that name are displayed.
|
||||
</p>
|
||||
<p>
|
||||
The beginning of our example is almost identical to our
|
||||
<code class="classname">ExampleDatabasePut</code>
|
||||
example program. We
|
||||
repeat that example code here for the sake of
|
||||
completeness. For a complete walk-through of it, see
|
||||
the previous section (<a class="xref" href="dpl_exampledatabaseput.html" title="ExampleDatabasePut.java">ExampleDatabasePut.java</a>).
|
||||
</p>
|
||||
<pre class="programlisting">package persist.gettingStarted;
|
||||
|
||||
import java.io.File;
|
||||
import java.io.IOException;
|
||||
|
||||
import com.sleepycat.je.DatabaseException;
|
||||
import com.sleepycat.persist.EntityCursor;
|
||||
|
||||
public class ExampleInventoryRead {
|
||||
|
||||
private static File myDbEnvPath =
|
||||
new File("/tmp/JEDB");
|
||||
|
||||
private DataAccessor da;
|
||||
|
||||
// Encapsulates the database environment.
|
||||
private static MyDbEnv myDbEnv = new MyDbEnv();
|
||||
|
||||
// The item to locate if the -s switch is used
|
||||
private static String locateItem;
|
||||
|
||||
private static void usage() {
|
||||
System.out.println("ExampleInventoryRead [-h <env directory>]" +
|
||||
"[-s <item to locate>]");
|
||||
System.exit(-1);
|
||||
}
|
||||
|
||||
public static void main(String args[]) {
|
||||
ExampleInventoryRead eir = new ExampleInventoryRead();
|
||||
try {
|
||||
eir.run(args);
|
||||
} catch (DatabaseException dbe) {
|
||||
System.err.println("ExampleInventoryRead: " + dbe.toString());
|
||||
dbe.printStackTrace();
|
||||
} finally {
|
||||
myDbEnv.close();
|
||||
}
|
||||
System.out.println("All done.");
|
||||
}
|
||||
|
||||
private void run(String args[])
|
||||
throws DatabaseException {
|
||||
// Parse the arguments list
|
||||
parseArgs(args);
|
||||
|
||||
myDbEnv.setup(myDbEnvPath, // path to the environment home
|
||||
true); // is this environment read-only?
|
||||
|
||||
// Open the data accessor. This is used to retrieve
|
||||
// persistent objects.
|
||||
da = new DataAccessor(myDbEnv.getEntityStore());
|
||||
|
||||
// If a item to locate is provided on the command line,
|
||||
// show just the inventory items using the provided name.
|
||||
// Otherwise, show everything in the inventory.
|
||||
if (locateItem != null) {
|
||||
showItem();
|
||||
} else {
|
||||
showAllInventory();
|
||||
}
|
||||
} </pre>
|
||||
<p>
|
||||
The first method that we provide is used to show inventory
|
||||
items related to a given inventory name. This method is called
|
||||
only if an inventory name is passed to
|
||||
<code class="classname">ExampleInventoryRead</code>
|
||||
via the <code class="literal">-s</code> option. Given the sample data
|
||||
that we provide with this example, each matching inventory name
|
||||
will result in the display of three inventory objects.
|
||||
</p>
|
||||
<p>
|
||||
To display these objects we use the
|
||||
<code class="classname">Inventory</code> class'
|
||||
<code class="literal">inventoryByName</code> secondary index to retrieve
|
||||
an <code class="classname">EntityCursor</code>, and then we iterate
|
||||
over the resulting objects using the cursor.
|
||||
</p>
|
||||
<p>
|
||||
Notice that this method calls
|
||||
<code class="methodname">displayInventoryRecord()</code>
|
||||
to display each individual object. We show this
|
||||
method a little later in the example.
|
||||
</p>
|
||||
<pre class="programlisting"> // Shows all the inventory items that exist for a given
|
||||
// inventory name.
|
||||
private void showItem() throws DatabaseException {
|
||||
|
||||
// Use the inventory name secondary key to retrieve
|
||||
// these objects.
|
||||
EntityCursor<Inventory> items =
|
||||
da.inventoryByName.subIndex(locateItem).entities();
|
||||
try {
|
||||
for (Inventory item : items) {
|
||||
displayInventoryRecord(item);
|
||||
}
|
||||
} finally {
|
||||
items.close();
|
||||
}
|
||||
} </pre>
|
||||
<p>
|
||||
Next we implement <code class="methodname">showAllInventory()</code>,
|
||||
which shows all of the <code class="classname">Inventory</code>
|
||||
objects in the store. To do this, we
|
||||
obtain an <code class="classname">EntityCursor</code>
|
||||
from the <code class="classname">Inventory</code> class'
|
||||
primary index and, again, we iterate using that cursor.
|
||||
</p>
|
||||
<pre class="programlisting"> // Displays all the inventory items in the store
|
||||
private void showAllInventory()
|
||||
throws DatabaseException {
|
||||
|
||||
// Get a cursor that will walk every
|
||||
// inventory object in the store.
|
||||
EntityCursor<Inventory> items =
|
||||
da.inventoryBySku.entities();
|
||||
|
||||
try {
|
||||
for (Inventory item : items) {
|
||||
displayInventoryRecord(item);
|
||||
}
|
||||
} finally {
|
||||
items.close();
|
||||
}
|
||||
} </pre>
|
||||
<p>
|
||||
Now we implement
|
||||
<code class="methodname">displayInventoryRecord()</code>. This
|
||||
uses the getter methods on the <code class="classname">Inventory</code>
|
||||
class to obtain the information that we want to display.
|
||||
The only thing interesting about this method is that we
|
||||
obtain <code class="classname">Vendor</code> objects within.
|
||||
The vendor objects are retrieved <code class="classname">Vendor</code>
|
||||
objects using their primary index. We get the key
|
||||
for the retrieval from the <code class="classname">Inventory</code>
|
||||
object that we are displaying at the time.
|
||||
</p>
|
||||
<pre class="programlisting"> private void displayInventoryRecord(Inventory theInventory)
|
||||
throws DatabaseException {
|
||||
|
||||
System.out.println(theInventory.getSku() + ":");
|
||||
System.out.println("\t " + theInventory.getItemName());
|
||||
System.out.println("\t " + theInventory.getCategory());
|
||||
System.out.println("\t " + theInventory.getVendor());
|
||||
System.out.println("\t\tNumber in stock: " +
|
||||
theInventory.getVendorInventory());
|
||||
System.out.println("\t\tPrice per unit: " +
|
||||
theInventory.getVendorPrice());
|
||||
System.out.println("\t\tContact: ");
|
||||
|
||||
Vendor theVendor =
|
||||
da.vendorByName.get(theInventory.getVendor());
|
||||
assert theVendor != null;
|
||||
|
||||
System.out.println("\t\t " + theVendor.getAddress());
|
||||
System.out.println("\t\t " + theVendor.getCity() + ", " +
|
||||
theVendor.getState() + " " + theVendor.getZipcode());
|
||||
System.out.println("\t\t Business Phone: " +
|
||||
theVendor.getBusinessPhoneNumber());
|
||||
System.out.println("\t\t Sales Rep: " +
|
||||
theVendor.getRepName());
|
||||
System.out.println("\t\t " +
|
||||
theVendor.getRepPhoneNumber());
|
||||
} </pre>
|
||||
<p>
|
||||
The last remaining parts of the example are used to parse
|
||||
the command line. This is not very
|
||||
interesting for our purposes here, but we show it anyway
|
||||
for the sake of completeness.
|
||||
</p>
|
||||
<pre class="programlisting"> protected ExampleInventoryRead() {}
|
||||
|
||||
private static void parseArgs(String args[]) {
|
||||
for(int i = 0; i < args.length; ++i) {
|
||||
if (args[i].startsWith("-")) {
|
||||
switch(args[i].charAt(1)) {
|
||||
case 'h':
|
||||
myDbEnvPath = new File(args[++i]);
|
||||
break;
|
||||
case 's':
|
||||
locateItem = args[++i];
|
||||
break;
|
||||
default:
|
||||
usage();
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
} </pre>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="dpl_exampledatabaseput.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="dpl_example.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="baseapi.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">ExampleDatabasePut.java </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Part II. Programming with the Base API</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
109
docs/GettingStartedGuide/dpl_replace.html
Normal file
109
docs/GettingStartedGuide/dpl_replace.html
Normal file
|
|
@ -0,0 +1,109 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Replacing Entity Objects</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="persist_access.html" title="Chapter 5. Saving and Retrieving Objects" />
|
||||
<link rel="prev" href="dpl_delete.html" title="Deleting Entity Objects" />
|
||||
<link rel="next" href="dpl_example.html" title="Chapter 6. A DPL Example" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Replacing Entity Objects</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="dpl_delete.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 5. Saving and Retrieving Objects</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="dpl_example.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="dpl_replace"></a>Replacing Entity Objects</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
To modify a stored entity object, retrieve it, update
|
||||
it, then put it back to the entity store:
|
||||
</p>
|
||||
<pre class="programlisting">
|
||||
SimpleEntityClass sec = sda.pIdx.get("keyone");
|
||||
sec.setSKey("skeyoneupdated");
|
||||
sda.pIdx.put(sec);
|
||||
</pre>
|
||||
<p>
|
||||
Note that because we updated a field on the object that is
|
||||
a secondary key, this object will now be accessible by the
|
||||
secondary key of <code class="literal">skeyoneupdated</code> instead
|
||||
of the previous value, which was <code class="literal">skeyone</code>
|
||||
</p>
|
||||
<p>
|
||||
Be aware that if you modify the object's primary key, the behavior is
|
||||
somewhat different. In this case, you cause a new instance
|
||||
of the object to be created in the store, instead of
|
||||
replacing an existing instance:
|
||||
</p>
|
||||
<pre class="programlisting">// Results in two objects in the store. One with a
|
||||
// primary index of "keyfive" and the other with primary index of
|
||||
//'keyfivenew'.
|
||||
SimpleEntityClass sec = sda.pIdx.get("keyfive");
|
||||
sec.setPKey("keyfivenew");
|
||||
sda.pIdx.put(sec); </pre>
|
||||
<p>
|
||||
Finally, if you are iterating over a collection of objects
|
||||
using an <code class="classname">EntityCursor</code>, you can
|
||||
update each object in turn using
|
||||
<code class="methodname">EntityCursor.update()</code>. Note,
|
||||
however, that you must be iterating using a
|
||||
<code class="classname">PrimaryIndex</code>; this operation is not
|
||||
allowed if you are using a
|
||||
<code class="classname">SecondaryIndex</code>.
|
||||
</p>
|
||||
<p>
|
||||
For example, the following iterates over every
|
||||
<code class="classname">SimpleEntityClass</code> object in the entity
|
||||
store, and it changes them all so that they have a
|
||||
secondary index of <code class="literal">updatedskey</code>:
|
||||
</p>
|
||||
<pre class="programlisting">EntityCursor<SimpleEntityClass> sec_pcursor = sda.pIdx.entities();
|
||||
for (SimpleEntityClass sec : sec_pcursor) {
|
||||
sec.setSKey("updatedskey");
|
||||
sec_pcursor.update(item);
|
||||
}
|
||||
sec_pcursor.close(); </pre>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="dpl_delete.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="persist_access.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="dpl_example.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Deleting Entity Objects </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Chapter 6. A DPL Example</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
419
docs/GettingStartedGuide/dplindexcreate.html
Normal file
419
docs/GettingStartedGuide/dplindexcreate.html
Normal file
|
|
@ -0,0 +1,419 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Creating Indexes</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="persist_index.html" title="Chapter 4. Working with Indices" />
|
||||
<link rel="prev" href="persist_index.html" title="Chapter 4. Working with Indices" />
|
||||
<link rel="next" href="persist_access.html" title="Chapter 5. Saving and Retrieving Objects" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Creating Indexes</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="persist_index.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 4. Working with Indices</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="persist_access.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="dplindexcreate"></a>Creating Indexes</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="toc">
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="dplindexcreate.html#dplprimaryidxdecl">Declaring Primary Indexes</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="dplindexcreate.html#dplsecondaryidxdecl">Declaring Secondary Indexes</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="dplindexcreate.html#foreignkey">Foreign Key Constraints</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</div>
|
||||
<p>
|
||||
To create an index using the DPL, you use Java
|
||||
annotations to declare which feature on the class is used
|
||||
for the primary index, and which features (if any) are to
|
||||
be used as secondary indexes.
|
||||
</p>
|
||||
<p>
|
||||
All entity classes stored in the DPL must have a
|
||||
primary index declared for it.
|
||||
</p>
|
||||
<p>
|
||||
Entity classes can have zero or more secondary
|
||||
indexes declared for them. There is no limit on the
|
||||
number of secondary indexes that you can declare.
|
||||
</p>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="dplprimaryidxdecl"></a>Declaring Primary Indexes</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
You declare a primary key for an entity class by
|
||||
using the <code class="literal">@PrimaryKey</code>
|
||||
annotation. This annotation must appear
|
||||
immediately before the data member which
|
||||
represents the class's primary key. For example:
|
||||
</p>
|
||||
<pre class="programlisting">package persist.gettingStarted;
|
||||
|
||||
import com.sleepycat.persist.model.Entity;
|
||||
import com.sleepycat.persist.model.PrimaryKey;
|
||||
|
||||
@Entity
|
||||
public class Vendor {
|
||||
|
||||
private String address;
|
||||
private String bizPhoneNumber;
|
||||
private String city;
|
||||
private String repName;
|
||||
private String repPhoneNumber;
|
||||
private String state;
|
||||
|
||||
// Primary key is the vendor's name
|
||||
// This assumes that the vendor's name is
|
||||
// unique in the database.
|
||||
@PrimaryKey
|
||||
private String vendor;
|
||||
|
||||
... </pre>
|
||||
<p>
|
||||
For this class, the <code class="literal">vendor</code> value is set for an individual
|
||||
<code class="classname">Vendor</code> class object by
|
||||
the <code class="methodname">setVendorName()</code>
|
||||
method. If our example code fails to set this
|
||||
value before storing the object, the data
|
||||
member used to store the primary key is set to a
|
||||
null value. This would result in a runtime
|
||||
error.
|
||||
</p>
|
||||
<p>
|
||||
You can avoid the need to explicitly set a
|
||||
value for a class's primary index by specifying
|
||||
a sequence to be used for the primary key. This
|
||||
results in an unique integer value being used
|
||||
as the primary key for each stored object.
|
||||
</p>
|
||||
<p>
|
||||
You declare a sequence is to be used by specifying
|
||||
the <code class="literal">sequence</code> keyword to the
|
||||
<code class="literal">@PrimaryKey</code> annotation. You must
|
||||
also provide a name for the sequence. For example:
|
||||
For example:
|
||||
</p>
|
||||
<pre class="programlisting">@PrimaryKey(sequence="Sequence_Namespace")
|
||||
long myPrimaryKey; </pre>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="dplsecondaryidxdecl"></a>Declaring Secondary Indexes</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
To declare a secondary index, we use the
|
||||
<code class="literal">@SecondaryKey</code> annotation. Note
|
||||
that when we do this, we must declare what sort of
|
||||
an index it is; that is, what is its relationship to
|
||||
other data in the data store.
|
||||
</p>
|
||||
<p>
|
||||
The <span class="emphasis"><em>kind</em></span> of indices that we
|
||||
can declare are:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
<code class="literal">ONE_TO_ONE</code>
|
||||
</p>
|
||||
<p>
|
||||
This relationship indicates that
|
||||
the secondary key is unique to the
|
||||
object. If an object is stored with a
|
||||
secondary key that already
|
||||
exists in the data store, a run
|
||||
time error is raised.
|
||||
</p>
|
||||
<p>
|
||||
For example, a person object might
|
||||
be stored with a primary key of a
|
||||
social security number (in the US),
|
||||
with a secondary key of the
|
||||
person's employee number. Both
|
||||
values are expected to be unique in
|
||||
the data store.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="literal">MANY_TO_ONE</code>
|
||||
</p>
|
||||
<p>
|
||||
Indicates that the secondary key
|
||||
may be used for multiple
|
||||
objects in the data store. That is,
|
||||
the key appears more than
|
||||
once, but for each stored object it
|
||||
can be used only once.
|
||||
</p>
|
||||
<p>
|
||||
Consider a data store that relates
|
||||
managers to employees. A given
|
||||
manager will have multiple
|
||||
employees, but each employee is
|
||||
assumed to have just one manager.
|
||||
In this case, the manager's
|
||||
employee number might be a
|
||||
secondary key, so that you can
|
||||
quickly locate all the objects
|
||||
related to that manager's
|
||||
employees.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="literal">ONE_TO_MANY</code>
|
||||
</p>
|
||||
<p>
|
||||
Indicates that the secondary key
|
||||
might be used more than once for a
|
||||
given object. Index keys
|
||||
themselves are assumed to be
|
||||
unique, but multiple instances of
|
||||
the index can be used per object.
|
||||
</p>
|
||||
<p>
|
||||
For example, employees might have
|
||||
multiple unique email addresses. In
|
||||
this case, any given object can be
|
||||
access by one or more email
|
||||
addresses. Each such address is
|
||||
unique in the data store, but each
|
||||
such address will relate to a
|
||||
single employee object.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="literal">MANY_TO_MANY</code>
|
||||
</p>
|
||||
<p>
|
||||
There can be multiple keys for
|
||||
any given object, and for any given
|
||||
key there can be many related
|
||||
objects.
|
||||
</p>
|
||||
<p>
|
||||
For example, suppose your
|
||||
organization has a shared
|
||||
resource, such as printers. You
|
||||
might want to track which
|
||||
printers a given employee can
|
||||
use (there might be more than
|
||||
one). You might also want to
|
||||
track which employees can use a
|
||||
specific printer. This
|
||||
represents a many-to-many
|
||||
relationship.
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<p>
|
||||
Note that for <code class="literal">ONE_TO_ONE</code> and
|
||||
<code class="literal">MANY_TO_ONE</code> relationships, you
|
||||
need a simple data member (not an array or
|
||||
collection) to hold the key. For
|
||||
<code class="literal">ONE_TO_MANY</code> and
|
||||
<code class="literal">MANY_TO_MANY</code> relationships, you
|
||||
need an array or collection to hold the keys:
|
||||
</p>
|
||||
<pre class="programlisting">@SecondaryKey(relate=ONE_TO_ONE)
|
||||
private String primaryEmailAddress = new String();
|
||||
|
||||
@SecondaryKey(relate=ONE_TO_MANY)
|
||||
private Set<String> emailAddresses = new HashSet<String>(); </pre>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="foreignkey"></a>Foreign Key Constraints</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
Sometimes a secondary index is related in some
|
||||
way to another entity class that is also
|
||||
contained in the data store. That is, the
|
||||
secondary key might be the primary key for
|
||||
another entity class. If this is the case, you
|
||||
can declare the foreign key constraint to make
|
||||
data integrity easier to accomplish.
|
||||
</p>
|
||||
<p>
|
||||
For example, you might have one class that is
|
||||
used to represent employees.
|
||||
You might have another that is used to
|
||||
represent corporate divisions. When you add or
|
||||
modify an employee record, you might want to
|
||||
ensure that the division to which the employee
|
||||
belongs is known to the data store. You do this
|
||||
by specifying a foreign key constraint.
|
||||
</p>
|
||||
<p>
|
||||
When a foreign key constraint is declared:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
When a new secondary key
|
||||
for the object is stored,
|
||||
it is checked to make sure
|
||||
it exists as a primary
|
||||
key for the related
|
||||
entity object. If it does
|
||||
not, a runtime error
|
||||
occurs.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
When a related entity is
|
||||
deleted (that is, a
|
||||
corporate division is
|
||||
removed from the data
|
||||
store), some action is
|
||||
automatically taken for
|
||||
the entities that refer to
|
||||
this object (that is, the
|
||||
employee objects). Exactly
|
||||
what that action is, is
|
||||
definable by you. See
|
||||
below.
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<p>
|
||||
When a related entity is deleted from the data
|
||||
store, one of the following actions are taken:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
<code class="literal">ABORT</code>
|
||||
</p>
|
||||
<p>
|
||||
The delete operation is not
|
||||
allowed. A runtime error is
|
||||
raised as a result of the
|
||||
operation. This is the
|
||||
default behavior.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="literal">CASCADE</code>
|
||||
</p>
|
||||
<p>
|
||||
All entities related to this
|
||||
one are deleted as well. For
|
||||
example, if you deleted a
|
||||
<code class="classname">Division</code>
|
||||
object, then all
|
||||
<code class="classname">Employee</code>
|
||||
objects that belonged to the
|
||||
division are also deleted.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="literal">NULLIFY</code>
|
||||
</p>
|
||||
<p>
|
||||
All entities related to the
|
||||
deleted entity are updated so
|
||||
that the pertinent data member
|
||||
is nullified. That is, if you
|
||||
deleted a division, then all
|
||||
employee objects related to
|
||||
that division would have their
|
||||
division key
|
||||
automatically set to null.
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<p>
|
||||
You declare a foreign key constraint by using
|
||||
the <code class="literal">relatedEntity</code> keyword. You
|
||||
declare the foreign key constraint deletion policy using the
|
||||
<code class="literal">onRelatedEntityDelete</code> keyword. For
|
||||
example, the following declares a foreign key
|
||||
constraint to <code class="classname">Division</code>
|
||||
class objects, and it causes related objects to
|
||||
be deleted if the <code class="classname">Division</code>
|
||||
class is deleted:
|
||||
</p>
|
||||
<pre class="programlisting">@SecondaryKey(relate=ONE_TO_ONE, relatedEntity=Division.class,
|
||||
onRelatedEntityDelete=CASCADE)
|
||||
private String division = new String(); </pre>
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="persist_index.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="persist_index.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="persist_access.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Chapter 4. Working with Indices </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Chapter 5. Saving and Retrieving Objects</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
412
docs/GettingStartedGuide/env.html
Normal file
412
docs/GettingStartedGuide/env.html
Normal file
|
|
@ -0,0 +1,412 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Chapter 2. Database Environments</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="prev" href="logfilesrevealed.html" title="Six Things Everyone Should Know about JE Log Files" />
|
||||
<link rel="next" href="envclose.html" title="Closing Database Environments" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Chapter 2. Database Environments</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="logfilesrevealed.html">Prev</a> </td>
|
||||
<th width="60%" align="center"> </th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="envclose.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="chapter" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title"><a id="env"></a>Chapter 2. Database Environments</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="toc">
|
||||
<p>
|
||||
<b>Table of Contents</b>
|
||||
</p>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="env.html#envopen">Opening Database Environments</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="env.html#multienv">Multiple Environments</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="env.html#multisubdir">Multiple Environment Subdirectories</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="env.html#multienvsharedcache">Configuring a Shared Cache for Multiple Environments</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="envclose.html">Closing Database Environments</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="EnvProps.html">Environment Properties</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="EnvProps.html#envconfig">The EnvironmentConfig Class</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="EnvProps.html#envhandleconfig">EnvironmentMutableConfig</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="envStats.html">Environment Statistics</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="dbenvUsageExample.html">Database Environment Management Example</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</div>
|
||||
<p>
|
||||
Regardless of whether you are using the DPL or the base API, you must use a database
|
||||
environment. Database environments encapsulate one or more databases. This encapsulation
|
||||
provides your threads with efficient access to your databases by allowing a single in-memory
|
||||
cache to be used for each of the databases contained in the environment. This encapsulation
|
||||
also allows you to group operations performed against multiple databases inside a single
|
||||
transaction (see the <em class="citetitle">Berkeley DB, Java Edition Getting Started with Transaction Processing</em> guide for more information).
|
||||
</p>
|
||||
<p>
|
||||
If you are using the base API, most commonly you use database environments to create and
|
||||
open databases (you close individual databases using the individual database handles). You
|
||||
can also use environments to delete and rename databases. For transactional applications,
|
||||
you use the environment to start transactions. For non-transactional applications, you use
|
||||
the environment to sync your in-memory cache to disk.
|
||||
</p>
|
||||
<p>
|
||||
If you are using the DPL, all of these things are still being done, but the DPL takes
|
||||
care of it for you. Under the DPL, the most common thing you will explicitly use an
|
||||
environment for is to obtain transaction handles.
|
||||
</p>
|
||||
<p>
|
||||
|
||||
Regardless of the API that you use, you also use the database environment for
|
||||
administrative and configuration activities related to your database log files and the
|
||||
in-memory cache.
|
||||
|
||||
See <a class="xref" href="administration.html" title="Chapter 12. Administering Berkeley DB Java Edition Applications">Administering Berkeley DB Java Edition Applications</a> for
|
||||
more information.
|
||||
</p>
|
||||
<p>
|
||||
To find out how to use environments with a transaction-protected application, see the
|
||||
<em class="citetitle">Berkeley DB, Java Edition Getting Started with Transaction Processing</em> guide.
|
||||
</p>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="envopen"></a>Opening Database Environments</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="toc">
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="env.html#multienv">Multiple Environments</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="env.html#multisubdir">Multiple Environment Subdirectories</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="env.html#multienvsharedcache">Configuring a Shared Cache for Multiple Environments</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</div>
|
||||
<p>
|
||||
You open a database environment by instantiating an <code class="classname">Environment</code>
|
||||
object. You must provide to the constructor the name of the on-disk directory where the
|
||||
environment is to reside. This directory location must exist or the open will fail.
|
||||
</p>
|
||||
<p>
|
||||
By default, the environment is not created for you if it does not exist. Set the <a class="link" href="EnvProps.html" title="Environment Properties">creation property</a> to <code class="literal">true</code> if you
|
||||
want the environment to be created. For example:
|
||||
</p>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.je.DatabaseException;
|
||||
import com.sleepycat.je.Environment;
|
||||
import com.sleepycat.je.EnvironmentConfig;
|
||||
|
||||
import java.io.File;
|
||||
|
||||
...
|
||||
|
||||
// Open the environment. Allow it to be created if it does not
|
||||
// already exist.
|
||||
Environment myDbEnvironment = null;
|
||||
|
||||
try {
|
||||
EnvironmentConfig envConfig = new EnvironmentConfig();
|
||||
envConfig.setAllowCreate(true);
|
||||
myDbEnvironment = new Environment(new File("/export/dbEnv"),
|
||||
envConfig);
|
||||
} catch (DatabaseException dbe) {
|
||||
// Exception handling goes here
|
||||
} </pre>
|
||||
<p>
|
||||
Opening an environment usually causes some background threads to be started. JE uses
|
||||
these threads for log file cleaning and some administrative tasks. However, these
|
||||
threads will only be opened once per process, so if you open the same environment more
|
||||
than once from within the same process, there is no performance impact on your
|
||||
application. Also, if you open the environment as read-only, then the background
|
||||
threads (with the exception of the evictor thread) are not started.
|
||||
</p>
|
||||
<p>
|
||||
Note that opening your environment causes normal recovery to be run. This
|
||||
causes your databases to be brought into a consistent state relative to the
|
||||
changed data found in your log files.
|
||||
See <a class="xref" href="backuprestore.html#databaselogs" title="Databases and Log Files">Databases and Log Files</a>
|
||||
for more information.
|
||||
</p>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="multienv"></a>Multiple Environments</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
Most JE applications only need a single database environment because any
|
||||
number of databases can be created in a single environment, and the
|
||||
total size of the data in an environment is not limited. That said,
|
||||
your application can open and use as many environments as you have disk and
|
||||
memory to manage. Also, you can instantiate
|
||||
multiple <code class="classname">Environment</code> objects
|
||||
for the same physical environment.
|
||||
</p>
|
||||
<p>
|
||||
The main reason for multiple environments is that an application must manage
|
||||
multiple unique data sets. By placing each data set in a separate environment,
|
||||
the application can gain real advantages in manageability of the data, and with
|
||||
application performance. By placing each data set in a unique environment,
|
||||
a separate set of log files is created and maintained in a separate directory,
|
||||
and so you can manipulate the log files for each data set separately.
|
||||
That is, you can:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
Backup, restore or delete a single data set
|
||||
separately by copying or removing the files for its environment.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Balance the load between machines by moving the files for a
|
||||
single data set from one machine to another.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Improve I/O performance by placing each data set on a separate
|
||||
physical disk.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Delete individual data sets very efficiently by removing the
|
||||
environment's log files. This is much more efficient than
|
||||
deleting individual database records and is also move
|
||||
efficient than removing databases, and so can be a real benefit
|
||||
if you are managing large temporary data sets that must be
|
||||
frequently deleted.
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<p>
|
||||
Be aware that there is a downside to using multiple environments. In particular,
|
||||
understand that a single transaction cannot include changes
|
||||
made in more than one environment. If you need to perform a set of
|
||||
operations in more than one data set atomically (with a single
|
||||
transaction), use a single environment and distinguish the data sets
|
||||
using some other method.
|
||||
</p>
|
||||
<p>
|
||||
For example, an application running a hosted service for multiple clients may
|
||||
wish to keep each client's data set separate. You can do this with multiple
|
||||
environments, but then you can operate on all data sets atomically. If you need
|
||||
to wrap operations for multiple data sets in a single transaction, consider some
|
||||
other approach to keeping the data sets separate.
|
||||
</p>
|
||||
<p>
|
||||
You can, for example, distinguish each data set using a unique key range within
|
||||
a single database. Or you can create a secondary key that identifies the data
|
||||
set. Or you could use separate databases for each dataset. All of these
|
||||
approaches allow you to maintain multiple distinct dataset within a single
|
||||
environment, but each obviously adds a level of complexity to your code over
|
||||
what is required to simply use a unique environment for each data set.
|
||||
</p>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="multisubdir"></a>Multiple Environment Subdirectories</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
You can spread your JE environment across multiple subdirectories. This allows you
|
||||
to improve data throughput by spreading disk I/O across multiple disks or filesystems.
|
||||
Environment subdirectories reside in the environment home directory and are named
|
||||
<code class="literal">data001/</code> through <code class="literal">dataNNN/</code>, consecutively, where
|
||||
<code class="literal">NNN</code> is the number of subdirectories that you want to use. Typically,
|
||||
each of the <code class="literal">dataNNN/</code> names are symbolic links to actual directories
|
||||
which reside on separate file systems or disks. Alternatively, each subdirectory can
|
||||
be mount points for filesystems which reside on different disk drives.
|
||||
</p>
|
||||
<p>
|
||||
You control the number of subdirectories you want to use with the
|
||||
<code class="literal">je.log.nDataDirectories</code> property in the
|
||||
<code class="literal">je.properties</code> file. This value must be set prior to opening the
|
||||
environment, and the subdirectories must already exist at that time. The value set for
|
||||
this property can not change over the course of the environment's lifetime, or an
|
||||
exception is thrown when you attempt to open the environment.
|
||||
</p>
|
||||
<p>
|
||||
The default value for <code class="literal">je.log.nDataDirectories</code> is 0, and this means no
|
||||
subdirectories are in use for the environment. A value greater than 0 indicates the
|
||||
number of subdirectories to use, and that number of subdirectories must exist prior to
|
||||
opening the environment.
|
||||
</p>
|
||||
<p>
|
||||
For example, if you set <code class="literal">je.log.nDataDirectories</code> to 3, then the first
|
||||
time you open the environment (and for every environment open after that) your
|
||||
environment home directory must contain three subdirectories named
|
||||
<code class="literal">data001</code>, <code class="literal">data002</code> and <code class="literal">data003</code>.
|
||||
This causes your JE log files (the <code class="literal">*.jdb</code> files) to be spread
|
||||
evenly across those three subdirectories. Finally, if you change the value of
|
||||
<code class="literal">je.log.nDataDirectories</code> without first completely deleting your
|
||||
environment, then your application will throw exceptions when you open your environment.
|
||||
</p>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="multienvsharedcache"></a>Configuring a Shared Cache for Multiple Environments</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
By default, each distinct JE environment has a separate, private
|
||||
in-memory cache. If a single JVM process will keep open multiple
|
||||
environments at the same time, it is strongly recommended that all such
|
||||
environments are configured to use a shared cache. A shared cache makes
|
||||
much more efficient use of memory than separate private caches.
|
||||
</p>
|
||||
<p>
|
||||
For example, imagine that you open 5 environments in a single process
|
||||
and a total of 500 MB of memory is available for caching. Using private
|
||||
caches, you could configure each cache to be 100 MB. If one of the
|
||||
environments has a larger active data set than the others, it will
|
||||
not be able to take advantage of unused memory in the other environment
|
||||
caches. By using a shared cache, multiple open environments will make
|
||||
better use of memory because the cache LRU algorithm is applied across
|
||||
all information in all enviornments sharing the cache.
|
||||
</p>
|
||||
<p>
|
||||
In order to configure an environment to use a shared cache, set
|
||||
<code class="methodname">EnvironmentConfig.setSharedCache()</code>
|
||||
to <code class="literal">true</code>. This must be set for every environment in the
|
||||
process that you want to use the shared cache. For example:
|
||||
</p>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.je.DatabaseException;
|
||||
import com.sleepycat.je.Environment;
|
||||
import com.sleepycat.je.EnvironmentConfig;
|
||||
|
||||
import java.io.File;
|
||||
|
||||
...
|
||||
|
||||
// Open the environment. Allow it to be created if it does not
|
||||
// already exist.
|
||||
Environment myEnv1 = null;
|
||||
Environment myEnv2 = null;
|
||||
|
||||
try {
|
||||
EnvironmentConfig envConfig = new EnvironmentConfig();
|
||||
envConfig.setAllowCreate(true);
|
||||
envConfig.setSharedCache(true);
|
||||
|
||||
myEnv1 = new Environment(new File("/export/dbEnv1"), envConfig);
|
||||
myEnv2 = new Environment(new File("/export/dbEnv2"), envConfig);
|
||||
} catch (DatabaseException dbe) {
|
||||
// Exception handling goes here
|
||||
} </pre>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="logfilesrevealed.html">Prev</a> </td>
|
||||
<td width="20%" align="center"> </td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="envclose.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Six Things Everyone Should Know about JE Log Files </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Closing Database Environments</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
102
docs/GettingStartedGuide/envStats.html
Normal file
102
docs/GettingStartedGuide/envStats.html
Normal file
|
|
@ -0,0 +1,102 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Environment Statistics</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="env.html" title="Chapter 2. Database Environments" />
|
||||
<link rel="prev" href="EnvProps.html" title="Environment Properties" />
|
||||
<link rel="next" href="dbenvUsageExample.html" title="Database Environment Management Example" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Environment Statistics</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="EnvProps.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 2. Database Environments</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="dbenvUsageExample.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="envStats"></a>Environment Statistics</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
JE offers a wealth of information that you can examine regarding your environment's operations. The majority
|
||||
of this information involves numbers relevant only to the JE developer and as such a description of those
|
||||
statistics is beyond the scope of this manual.
|
||||
</p>
|
||||
<p>
|
||||
However, one statistic that is very important (especially for
|
||||
long-running applications) is
|
||||
<code class="methodname">EnvironmentStats.getNCacheMiss()</code>.
|
||||
This statistic returns the total number of
|
||||
requests for database objects that were not serviceable from the cache.
|
||||
This number is important to the
|
||||
application administrator who is attempting to determine the proper size for the in-memory cache.
|
||||
|
||||
See <a class="xref" href="cachesize.html" title="Sizing the Cache">Sizing the Cache</a> for details.
|
||||
</p>
|
||||
<p>
|
||||
To obtain this statistic from your environment, call <code class="methodname">Environment.getStats()</code> to return
|
||||
an <code class="classname">EnvironmentStats</code> object. You can then call the
|
||||
<code class="methodname">EnvironmentStats.getNCacheMiss()</code> method. For example:
|
||||
</p>
|
||||
<a id="je_env5"></a>
|
||||
<pre class="programlisting">import com.sleepycat.je.Environment;
|
||||
|
||||
...
|
||||
|
||||
long cacheMisses = myEnv.getStats(null).getNCacheMiss();
|
||||
|
||||
...
|
||||
</pre>
|
||||
<p>
|
||||
Note that <code class="methodname">Environment.getStats()</code> can only obtain statistics from your application's
|
||||
process. In order for the application administrator to obtain this statistic, you must either
|
||||
use JMX to retrieve the statistic
|
||||
(see <a class="xref" href="jmx.html" title="JConsole and JMX Support">JConsole and JMX Support</a>)
|
||||
or you must print it for examination (for example, log the value once a minute).
|
||||
</p>
|
||||
<p>
|
||||
Remember that what is really important for cache sizing is the change in this value over time, and not the actual value
|
||||
itself. So you might consider offering a delta from one examination of this statistic to the next (a delta of 0 is
|
||||
desired while large deltas are an indication that the cache is too small).
|
||||
</p>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="EnvProps.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="env.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="dbenvUsageExample.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Environment Properties </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Database Environment Management Example</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
127
docs/GettingStartedGuide/envclose.html
Normal file
127
docs/GettingStartedGuide/envclose.html
Normal file
|
|
@ -0,0 +1,127 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Closing Database Environments</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="env.html" title="Chapter 2. Database Environments" />
|
||||
<link rel="prev" href="env.html" title="Chapter 2. Database Environments" />
|
||||
<link rel="next" href="EnvProps.html" title="Environment Properties" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Closing Database Environments</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="env.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 2. Database Environments</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="EnvProps.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="envclose"></a>Closing Database Environments</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
You close your environment by calling the <code class="methodname">Environment.close()</code>
|
||||
method. This method performs a checkpoint, so it is not necessary to perform a sync or a
|
||||
checkpoint explicitly before calling it. For information on checkpoints, see the
|
||||
<em class="citetitle">Berkeley DB, Java Edition Getting Started with Transaction Processing</em> guide. For information on syncs, see <a class="xref" href="backuprestore.html#syncs" title="Database Modifications and Syncs">Database Modifications and Syncs</a>.
|
||||
</p>
|
||||
<a id="je_env2"></a>
|
||||
<pre class="programlisting">import com.sleepycat.je.DatabaseException;
|
||||
|
||||
import com.sleepycat.je.Environment;
|
||||
|
||||
...
|
||||
|
||||
try {
|
||||
if (myDbEnvironment != null) {
|
||||
myDbEnvironment.close();
|
||||
}
|
||||
} catch (DatabaseException dbe) {
|
||||
// Exception handling goes here
|
||||
} </pre>
|
||||
<p>
|
||||
If you are using the DPL, then close your environment(s) only after all other store
|
||||
activities have completed and you have closed any stores currently opened in the
|
||||
environment. If you are using the base API, then close your environment(s) only after
|
||||
all other database activities have completed and you have closed any databases currently
|
||||
opened in the environment.
|
||||
</p>
|
||||
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
|
||||
<h3 class="title">Note</h3>
|
||||
<p>
|
||||
It is possible for the environment to close before JE's
|
||||
cleaner thread
|
||||
has finished its work. This happens if you perform a large number of deletes immediately
|
||||
before shutting down your environment. The result is that your log files may be quit a lot larger than you
|
||||
expect them to be because the cleaner thread has not had a chance to finish its work.
|
||||
</p>
|
||||
<p>
|
||||
See <a class="xref" href="backgroundthreads.html#cleaner" title="The Cleaner Thread">The Cleaner Thread</a> for
|
||||
details on the cleaner threads.
|
||||
</p>
|
||||
<p>
|
||||
If you want to make sure that the cleaner has finished running before the environment is closed,
|
||||
call <code class="methodname">Environment.cleanLog()</code> before calling
|
||||
<code class="methodname">Environment.close()</code>:
|
||||
</p>
|
||||
<a id="je_env2-1"></a>
|
||||
<pre class="programlisting">import com.sleepycat.je.DatabaseException;
|
||||
|
||||
import com.sleepycat.je.Environment;
|
||||
|
||||
...
|
||||
|
||||
try {
|
||||
if (myDbEnvironment != null) {
|
||||
myDbEnvironment.cleanLog(); // Clean the log before closing
|
||||
myDbEnvironment.close();
|
||||
}
|
||||
} catch (DatabaseException dbe) {
|
||||
// Exception handling goes here
|
||||
} </pre>
|
||||
</div>
|
||||
<p>
|
||||
Closing the last environment handle in your application causes all internal data structures
|
||||
to be released and the background threads to be stopped. If there are any opened databases,
|
||||
then JE will complain before closing them as well. At this time, and any on-going
|
||||
transactions are aborted. Also at this time any open cursors are also closed. However, it is recommended that you always close all cursor handles immediately after their use to ensure concurrency and to release resources such as page locks.
|
||||
</p>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="env.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="env.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="EnvProps.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Chapter 2. Database Environments </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Environment Properties</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
336
docs/GettingStartedGuide/getmultiple.html
Normal file
336
docs/GettingStartedGuide/getmultiple.html
Normal file
|
|
@ -0,0 +1,336 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Retrieving Multiple Objects</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="persist_access.html" title="Chapter 5. Saving and Retrieving Objects" />
|
||||
<link rel="prev" href="simpleget.html" title="Retrieving Objects from an Entity Store" />
|
||||
<link rel="next" href="dpl_entityjoin.html" title="Join Cursors" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Retrieving Multiple Objects</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="simpleget.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 5. Saving and Retrieving Objects</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="dpl_entityjoin.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="getmultiple"></a>Retrieving Multiple Objects</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="toc">
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="getmultiple.html#dpl_cursor_initialize">Cursor Initialization</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="getmultiple.html#dpl_dups">Working with Duplicate Keys</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="getmultiple.html#dpl_cursor_range">Key Ranges</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</div>
|
||||
<p>
|
||||
It is possible to iterate over every object referenced
|
||||
by a specific index. You may want to do this if, for
|
||||
example, you want to examine or modify every object
|
||||
accessible by a specific primary index.
|
||||
</p>
|
||||
<p>
|
||||
In addition, some indexes result in the retrieval of multiple
|
||||
objects. For example, <code class="literal">MANY_TO_ONE</code>
|
||||
secondary indexes can result in more than one object for any given
|
||||
key (also known as <span class="emphasis"><em>duplicate keys</em></span>).
|
||||
When this is the case, you must iterate
|
||||
over the resulting set of objects in order to examine
|
||||
each object in turn.
|
||||
</p>
|
||||
<p>
|
||||
There are two ways to iterate over a collection of
|
||||
objects as returned by an index. One is to use a
|
||||
standard Java <code class="classname">Iterator</code>, which you
|
||||
obtain using an <code class="classname">EntityCursor</code>,
|
||||
which in turn you can obtain from a <code class="classname">PrimaryIndex</code>:
|
||||
</p>
|
||||
<pre class="programlisting">PrimaryIndex<String,SimpleEntityClass> pi =
|
||||
store.getPrimaryIndex(String.class, SimpleEntityClass.class);
|
||||
EntityCursor<SimpleEntityClass> pi_cursor = pi.entities();
|
||||
try {
|
||||
Iterator<SimpleEntityClass> i = pi_cursor.iterator();
|
||||
while (i.hasNext()) {
|
||||
// Do something here
|
||||
}
|
||||
} finally {
|
||||
// Always close the cursor
|
||||
pi_cursor.close();
|
||||
} </pre>
|
||||
<p>
|
||||
Alternatively, you can use a Java "foreach" statement
|
||||
to iterate over object set:
|
||||
</p>
|
||||
<pre class="programlisting">PrimaryIndex<String,SimpleEntityClass> pi =
|
||||
store.getPrimaryIndex(String.class, SimpleEntityClass.class);
|
||||
EntityCursor<SimpleEntityClass> pi_cursor = pi.entities();
|
||||
try {
|
||||
for (SimpleEntityClass seci : pi_cursor) {
|
||||
// do something with each object "seci"
|
||||
}
|
||||
// Always make sure the cursor is closed when we are done with it.
|
||||
} finally {
|
||||
pi_cursor.close();
|
||||
} </pre>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="dpl_cursor_initialize"></a>Cursor Initialization</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
When a cursor is first opened, it is not
|
||||
positioned to any value; that is,
|
||||
it is not <span class="emphasis"><em>initialized</em></span>.
|
||||
Most of the <code class="classname">EntityCursor</code>
|
||||
methods that move a cursor will initialize it
|
||||
to either the first or last object, depending
|
||||
on whether the operation is moving the cursor
|
||||
forward (all <code class="literal">next...</code>
|
||||
methods) or backwards (all
|
||||
<code class="literal">prev...</code>) methods.
|
||||
</p>
|
||||
<p>
|
||||
You can also force a cursor, whether it is
|
||||
initialized or not, to return the first object
|
||||
by calling
|
||||
<code class="methodname">EntityCursor.first()</code>.
|
||||
Similarly, you can force a return of the last
|
||||
object using
|
||||
<code class="methodname">EntityCursor.last()</code>.
|
||||
</p>
|
||||
<p>
|
||||
Operations that do not move the cursor (such as
|
||||
<code class="methodname">EntityCursor.current()</code>
|
||||
or <code class="methodname">EntityCursor.delete()</code>
|
||||
will throw an
|
||||
<code class="classname">IllegalStateException</code>
|
||||
when used on an uninitialized cursor.
|
||||
</p>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="dpl_dups"></a>Working with Duplicate Keys</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
If you have duplicate secondary keys, you can return an
|
||||
<code class="classname">EntityIndex</code> class object for them
|
||||
using <code class="methodname">SecondaryIndex.subIndex()</code>
|
||||
Then, use that object's
|
||||
<code class="methodname">entities()</code>
|
||||
method to obtain an <code class="classname">EntityCursor</code>
|
||||
instance.
|
||||
</p>
|
||||
<p>
|
||||
For example:
|
||||
</p>
|
||||
<pre class="programlisting">PrimaryIndex<String,SimpleEntityClass> pi =
|
||||
store.getPrimaryIndex(String.class, SimpleEntityClass.class);
|
||||
|
||||
SecondaryIndex<String,String,SimpleEntityClass> si =
|
||||
store.getSecondaryIndex(pi, String.class, "sKey");
|
||||
|
||||
EntityCursor<SimpleEntityClass> sec_cursor =
|
||||
si.subIndex("skeyone").entities();
|
||||
|
||||
try {
|
||||
for (SimpleEntityClass seci : sec_cursor) {
|
||||
// do something with each object "seci"
|
||||
}
|
||||
// Always make sure the cursor is closed when we are done with it.
|
||||
} finally {
|
||||
sec_cursor.close(); } </pre>
|
||||
<p>
|
||||
Note that if you are working with duplicate keys, you can
|
||||
control how cursor iteration works by using the following
|
||||
<code class="classname">EntityCursor</code> methods:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
<code class="methodname">nextDup()</code>
|
||||
</p>
|
||||
<p>
|
||||
Moves the cursor to the next object with the
|
||||
same key as the cursor is currently
|
||||
referencing. That is, this method returns the
|
||||
next duplicate object. If no such object
|
||||
exists, this method returns
|
||||
<code class="literal">null</code>.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="methodname">prevDup()</code>
|
||||
</p>
|
||||
<p>
|
||||
Moves the cursor to the previous object with the
|
||||
same key as the cursor is currently
|
||||
referencing. That is, this method returns the
|
||||
previous duplicate object in the cursor's set
|
||||
of objects. If no such object exists, this method returns
|
||||
<code class="literal">null</code>.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="methodname">nextNoDup()</code>
|
||||
</p>
|
||||
<p>
|
||||
Moves the cursor to the next object in the
|
||||
cursor's set that has a key which is different
|
||||
than the key that the cursor is currently
|
||||
referencing. That is, this method skips all
|
||||
duplicate objects and returns the
|
||||
next non-duplicate object in the cursor's set
|
||||
of objects. If no such object exists, this method returns
|
||||
<code class="literal">null</code>.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="methodname">prevNoDup()</code>
|
||||
</p>
|
||||
<p>
|
||||
Moves the cursor to the previous object in the
|
||||
cursor's set that has a key which is different
|
||||
than the key that the cursor is currently
|
||||
referencing. That is, this method skips all
|
||||
duplicate objects and returns the
|
||||
previous non-duplicate object in the cursor's set
|
||||
of objects. If no such object exists, this method returns
|
||||
<code class="literal">null</code>.
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<p>
|
||||
For example:
|
||||
</p>
|
||||
<pre class="programlisting">PrimaryIndex<String,SimpleEntityClass> pi =
|
||||
store.getPrimaryIndex(String.class, SimpleEntityClass.class);
|
||||
|
||||
SecondaryIndex<String,String,SimpleEntityClass> si =
|
||||
store.getSecondaryIndex(pi, String.class, "sKey");
|
||||
|
||||
EntityCursor<SimpleEntityClass> sec_cursor =
|
||||
si.subIndex("skeyone").entities();
|
||||
|
||||
try {
|
||||
SimpleEntityClass sec;
|
||||
Iterator<SimpleEntityClass> i = sec_cursor.iterator();
|
||||
while (sec = i.nextNoDup() != null) {
|
||||
// Do something here
|
||||
}
|
||||
// Always make sure the cursor is closed when we are done with it.
|
||||
} finally {
|
||||
sec_cursor.close(); } </pre>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="dpl_cursor_range"></a>Key Ranges</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
You can restrict the scope of a cursor's movement
|
||||
by specifying a <span class="emphasis"><em>range</em></span> when you
|
||||
create the cursor. The cursor can then never be
|
||||
positioned outside of the specified range.
|
||||
</p>
|
||||
<p>
|
||||
When specifying a range, you indicate whether a
|
||||
range bound is <span class="emphasis"><em>inclusive</em></span> or
|
||||
<span class="emphasis"><em>exclusive</em></span> by providing a
|
||||
boolean value for each range.
|
||||
<code class="literal">true</code> indicates that the provided
|
||||
bound is inclusive, while <code class="literal">false</code>
|
||||
indicates that it is exclusive.
|
||||
</p>
|
||||
<p>
|
||||
You provide this information when you call
|
||||
<code class="classname">PrimaryIndex.entities()</code>
|
||||
or
|
||||
<code class="classname">SecondaryIndex.entities()</code>.
|
||||
For example, suppose you had a class indexed by
|
||||
numerical information. Suppose further that you
|
||||
wanted to examine only those objects with indexed
|
||||
values of 100 - 199. Then (assuming the numerical
|
||||
information is the primary index), you can bound
|
||||
your cursor as follows:
|
||||
</p>
|
||||
<pre class="programlisting">
|
||||
EntityCursor<SomeEntityClass> cursor =
|
||||
primaryIndex.entities(100, true, 200, false);
|
||||
|
||||
try {
|
||||
for (SomeEntityClass sec : cursor {
|
||||
// Do something here to objects ranged from 100 to 199
|
||||
}
|
||||
// Always make sure the cursor is closed when we are done with it.
|
||||
} finally {
|
||||
cursor.close(); } </pre>
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="simpleget.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="persist_access.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="dpl_entityjoin.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Retrieving Objects from an Entity Store </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Join Cursors</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
50
docs/GettingStartedGuide/gettingStarted.css
Normal file
50
docs/GettingStartedGuide/gettingStarted.css
Normal file
|
|
@ -0,0 +1,50 @@
|
|||
body { width: 45em;
|
||||
margin-left: 3em;
|
||||
font-family: Arial, Helvetica, sans-serif;
|
||||
font-size: 11pt;
|
||||
}
|
||||
|
||||
h2.title { margin-left: -1em;
|
||||
font-family: Verdana, serif;
|
||||
font-size: 16pt;
|
||||
}
|
||||
|
||||
h3.title { font-family: Verdana, serif;
|
||||
font-size: 14pt;
|
||||
}
|
||||
|
||||
pre.programlisting {
|
||||
font-family: monospace;
|
||||
background-color: #eae8e9;
|
||||
}
|
||||
|
||||
div.navheader { font-size: 10pt;
|
||||
width: 60em;
|
||||
margin-left: -2em;
|
||||
}
|
||||
|
||||
div.navheader table tr td { font-size: 10pt; }
|
||||
|
||||
div.navfooter { font-size: 10pt;
|
||||
width: 60em;
|
||||
margin-left: -2em;
|
||||
}
|
||||
div.navfooter table tr td { font-size: 10pt; }
|
||||
|
||||
span.emphasis { font-style: italic;}
|
||||
|
||||
div.appendix div.informaltable { font-size: 9pt; }
|
||||
div.appendix div.informaltable td { vertical-align: top; }
|
||||
div.appendix div.informaltable p { margin-top: .25em; }
|
||||
div.appendix div.informaltable p { margin-bottom: .25em; }
|
||||
|
||||
div.variablelist dl dt {margin-top: 1em; }
|
||||
|
||||
div.libver p {
|
||||
font-size: 8pt;
|
||||
width: 30%;
|
||||
margin-left: 2px;
|
||||
margin-right: 2px;
|
||||
padding-top: 3px;
|
||||
padding-bottom: 3px;
|
||||
}
|
||||
103
docs/GettingStartedGuide/gettingit.html
Normal file
103
docs/GettingStartedGuide/gettingit.html
Normal file
|
|
@ -0,0 +1,103 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Getting and Using JE</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="introduction.html" title="Chapter 1. Introduction to Berkeley DB Java Edition" />
|
||||
<link rel="prev" href="jmx.html" title="JConsole and JMX Support" />
|
||||
<link rel="next" href="jeexceptions.html" title="JE Exceptions" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Getting and Using JE </th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="jmx.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 1. Introduction to Berkeley DB Java Edition </th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="jeexceptions.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="gettingit"></a>Getting and Using JE </h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
You can obtain JE by visiting the JE download page: <a class="ulink" href="http://www.oracle.com/technetwork/database/database-technologies/berkeleydb/downloads/index.html" target="_top">http://www.oracle.com/technetwork/database/database-technologies/berkeleydb/downloads/index.html</a>.
|
||||
</p>
|
||||
<p>
|
||||
To install JE, untar or unzip the distribution to the
|
||||
directory of your choice. If you use unzip, make sure to specify
|
||||
the <code class="literal">-U</code> option in order to preserve case.
|
||||
</p>
|
||||
<p>
|
||||
For more information on installing JE, see
|
||||
<span class="emphasis"><em>JE_HOME</em></span><code class="literal">/docs/relnotes.html</code>,
|
||||
where <span class="emphasis"><em>JE_HOME</em></span> is the directory where you
|
||||
unpacked JE.
|
||||
</p>
|
||||
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
|
||||
<h3 class="title">Note</h3>
|
||||
<p>
|
||||
JE is compatible with Java SE 8 (64-bit), and has been
|
||||
tested and certified against Oracle Java SE 8 and IBM Java IBM
|
||||
J9. It is recommended that you upgrade to the latest Java
|
||||
releases to take advantage of the latest bug fixes and
|
||||
performance improvements. The release notes included in the
|
||||
JE download specify the exact Java versions that have been
|
||||
used for certification.
|
||||
</p>
|
||||
<p>
|
||||
Linux, Oracle Solaris, and AIX are officially supported platforms for
|
||||
JE. Both Oracle Solaris x86 and Oracle Solaris SPARC are
|
||||
supported. A 64 bit JVM is required in order to run JE.
|
||||
</p>
|
||||
</div>
|
||||
<p>
|
||||
You can use JE with your application by adding
|
||||
<span class="emphasis"><em>JE_HOME</em></span><code class="literal">/lib/je-<version>.jar</code>
|
||||
to your application's classpath.
|
||||
</p>
|
||||
<p>
|
||||
Beyond this manual, you can find documentation for JE at
|
||||
<span class="emphasis"><em>JE_HOME</em></span><code class="literal">/docs/index.html</code>
|
||||
directory. In particular, complete Javadoc for the JE API set
|
||||
is available at
|
||||
<span class="emphasis"><em>JE_HOME</em></span><code class="literal">/docs/java/index.html</code>.
|
||||
</p>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="jmx.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="introduction.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="jeexceptions.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">JConsole and JMX Support </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> JE Exceptions</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
128
docs/GettingStartedGuide/hotfailover.html
Normal file
128
docs/GettingStartedGuide/hotfailover.html
Normal file
|
|
@ -0,0 +1,128 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Hot Standby</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="backuprestore.html" title="Chapter 11. Backing up and Restoring Berkeley DB Java Edition Applications" />
|
||||
<link rel="prev" href="catastrophicrecovery.html" title="Performing Catastrophic Recovery" />
|
||||
<link rel="next" href="administration.html" title="Chapter 12. Administering Berkeley DB Java Edition Applications" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Hot Standby</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="catastrophicrecovery.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 11. Backing up and Restoring Berkeley DB Java Edition Applications</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="administration.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="hotfailover"></a>Hot Standby</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
As a final backup/recovery strategy, you can create a hot standby. Note that using hot standbys requires
|
||||
your application to be able to specify its environment home directory at application startup time. Most
|
||||
application developers allow the environment home directory to be identified using a command line option or a
|
||||
configuration or properties file. If your application has its
|
||||
environment home hard-coded into it, you cannot use hot standbys.
|
||||
</p>
|
||||
<p>
|
||||
You create a hot standby by periodically backing up your database to an alternative
|
||||
location on disk. Usually this alternative location is on a separate physical drive from
|
||||
where you normally keep your database, but if multiple drives are not available then you
|
||||
should at least put the hot standby on a separate disk partition.
|
||||
</p>
|
||||
<p>
|
||||
You failover to your hot standby by causing your application to reopen its environment using the hot standby
|
||||
location.
|
||||
</p>
|
||||
<p>
|
||||
Note that a hot standby should not be used as a substitute for backing up and archiving your data to a safe
|
||||
location away from your operating environment. Even if your data is spread across multiple physical disks, a
|
||||
truly serious catastrophe (fires, malevolent software viruses,
|
||||
faulty disk controllers, and so forth)
|
||||
can still cause you to lose your data.
|
||||
</p>
|
||||
<p>
|
||||
To create and maintain a hot standby:
|
||||
</p>
|
||||
<div class="orderedlist">
|
||||
<ol type="1">
|
||||
<li>
|
||||
<p>
|
||||
Copy all log files (<code class="filename">*.jdb</code>) from your environment
|
||||
directory to the location where you want to keep your standby. Either a hot
|
||||
or an offline backup can be used for this purpose, but typically a hot
|
||||
standby is initially created by taking an offline backup of your database.
|
||||
This ensures that you have captured the contents of your in-memory cache.
|
||||
</p>
|
||||
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
|
||||
<h3 class="title">Note</h3>
|
||||
<p>
|
||||
If you are using subdirectories to store your log files, then you must backup
|
||||
the subdirectories, making sure to keep log files in the subdirectory in which
|
||||
JE placed them. For information on using subdirectories to store your log
|
||||
files, see <a class="xref" href="env.html#multisubdir" title="Multiple Environment Subdirectories">Multiple Environment Subdirectories</a>.
|
||||
</p>
|
||||
</div>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Periodically copy to your standby directory any log files that were changed or created since the
|
||||
time of your last copy. Most backup software is capable of performing this kind of an incremental
|
||||
backup for you.
|
||||
</p>
|
||||
<p>
|
||||
Note that the frequency of your incremental copies determines the amount of data that is at risk due to catastrophic
|
||||
failures. For example, if you perform the incremental copy once an hour then at most your hot standby is an hour behind
|
||||
your production database, and so you are risking at most an hours worth of database changes.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Remove any <code class="filename">*.jdb</code> files from the hot standby directory that have been removed or
|
||||
renamed to <code class="filename">.del</code> files in the primary directory. This is not necessary for
|
||||
consistency, but will help to reduce disk space consumed by the hot standby.
|
||||
</p>
|
||||
</li>
|
||||
</ol>
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="catastrophicrecovery.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="backuprestore.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="administration.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Performing Catastrophic Recovery </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Chapter 12. Administering Berkeley DB Java Edition Applications</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
1101
docs/GettingStartedGuide/index.html
Normal file
1101
docs/GettingStartedGuide/index.html
Normal file
File diff suppressed because it is too large
Load diff
398
docs/GettingStartedGuide/indexes.html
Normal file
398
docs/GettingStartedGuide/indexes.html
Normal file
|
|
@ -0,0 +1,398 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Chapter 10. Secondary Databases</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="baseapi.html" title="Part II. Programming with the Base API" />
|
||||
<link rel="prev" href="cursorUsage.html" title="Cursor Example" />
|
||||
<link rel="next" href="keyCreator.html" title="Implementing Key Creators" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Chapter 10. Secondary Databases</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="cursorUsage.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Part II. Programming with the Base API</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="keyCreator.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="chapter" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title"><a id="indexes"></a>Chapter 10. Secondary Databases</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="toc">
|
||||
<p>
|
||||
<b>Table of Contents</b>
|
||||
</p>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="indexes.html#DbAssociate">Opening and Closing Secondary Databases</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="keyCreator.html">Implementing Key
|
||||
<span>Creators</span>
|
||||
|
||||
</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="secondaryProps.html">Secondary Database Properties</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="readSecondary.html">Reading Secondary Databases</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="secondaryDelete.html">Deleting Secondary Database Records</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="secondaryCursor.html">
|
||||
<span>Using Secondary Cursors</span>
|
||||
|
||||
</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="joins.html">Database Joins</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="joins.html#joinUsage">Using Join Cursors</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="joins.html#joinconfig">JoinCursor Properties</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="indexusage.html">Secondary Database Example</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="indexusage.html#secondaryMyDbEnv">Opening Secondary Databases with
|
||||
MyDbEnv</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="indexusage.html#exampleReadSecondaries">Using Secondary Databases with ExampleInventoryRead</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
</dl>
|
||||
</div>
|
||||
<p>
|
||||
Usually you find database records by means of the record's key. However,
|
||||
the key that you use for your record will not always contain the
|
||||
information required to provide you with rapid access to the data that you
|
||||
want to retrieve. For example, suppose your
|
||||
<code class="classname">Database</code>
|
||||
|
||||
contains records related to users. The key might be a string that is some
|
||||
unique identifier for the person, such as a user ID. Each record's data,
|
||||
however, would likely contain a complex object containing details about
|
||||
people such as names, addresses, phone numbers, and so forth.
|
||||
While your application may frequently want to query a person by user
|
||||
ID (that is, by the information stored in the key), it may also on occasion
|
||||
want to locate people by, say, their name.
|
||||
</p>
|
||||
<p>
|
||||
Rather than iterate through all of the records in your database, examining
|
||||
each in turn for a given person's name, you create indexes based on names
|
||||
and then just search that index for the name that you want. You can do this
|
||||
using secondary databases. In JE, the
|
||||
<code class="classname">Database</code>
|
||||
|
||||
that contains your data is called a
|
||||
<span class="emphasis"><em>primary database</em></span>. A database that provides an
|
||||
alternative set of keys to access that data is called a <span class="emphasis"><em>secondary
|
||||
database</em></span><span>,
|
||||
and these are managed using <code class="classname">SecondaryDatabase</code>
|
||||
class objects.</span> In a secondary database, the keys are your alternative
|
||||
(or secondary) index, and the data corresponds to a primary record's key.
|
||||
</p>
|
||||
<p>
|
||||
You create a secondary database by using a <code class="classname">SecondaryConfig</code>
|
||||
class object to identify an implementation of a
|
||||
<code class="classname">SecondaryKeyCreator</code>
|
||||
class object that is used to create keys based on data found in the primary
|
||||
database. You then pass this <code class="classname">SecondaryConfig</code>
|
||||
object to the <code class="classname">SecondaryDatabase</code> constructor.
|
||||
</p>
|
||||
<p>
|
||||
Once opened, JE manages secondary databases for you. Adding or deleting
|
||||
records in your primary database causes JE to update the secondary as
|
||||
necessary. Further, changing a record's data in the primary database may cause
|
||||
JE to modify a record in the secondary, depending on whether the change
|
||||
forces a modification of a key in the secondary database.
|
||||
</p>
|
||||
<p>
|
||||
Note that you can not write directly to a secondary database.
|
||||
|
||||
<span>While methods
|
||||
exist on <code class="classname">SecondaryDatabase</code> and
|
||||
<code class="classname">SecondaryCursor</code> that appear to allow this, they in
|
||||
fact always throw
|
||||
<code class="classname">UnsupportedOperationException</code>.</span>
|
||||
|
||||
|
||||
|
||||
To change the data referenced by a
|
||||
<code class="classname">SecondaryDatabase</code>
|
||||
|
||||
record, modify the primary database instead. The exception to this rule is
|
||||
that delete operations are allowed on the
|
||||
<span><code class="classname">SecondaryDatabase</code> object.</span>
|
||||
|
||||
|
||||
See <a class="xref" href="secondaryDelete.html" title="Deleting Secondary Database Records">Deleting Secondary Database Records</a> for more
|
||||
information.
|
||||
</p>
|
||||
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
|
||||
<h3 class="title">Note</h3>
|
||||
<p>
|
||||
|
||||
Secondary database records are updated/created by JE
|
||||
only if the
|
||||
<span><code class="methodname">SecondaryKeyCreator.createSecondaryKey()</code> method</span>
|
||||
|
||||
returns
|
||||
<span><code class="literal">true</code>.</span>
|
||||
|
||||
If
|
||||
<code class="literal">false</code>
|
||||
|
||||
is returned, then JE will not add the key to the secondary database, and
|
||||
in the event of a record update it will remove any existing key.
|
||||
|
||||
|
||||
|
||||
</p>
|
||||
<p>
|
||||
See <a class="xref" href="keyCreator.html" title="Implementing Key Creators">Implementing Key
|
||||
<span>Creators</span>
|
||||
|
||||
</a> for more
|
||||
<span>information on this interface and method.</span>
|
||||
|
||||
|
||||
</p>
|
||||
</div>
|
||||
<p>
|
||||
When you read a record from a secondary database, JE automatically
|
||||
returns
|
||||
<span>the key and data</span>
|
||||
|
||||
from the corresponding record in the primary database.
|
||||
<span>
|
||||
|
||||
</span>
|
||||
</p>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="DbAssociate"></a>Opening and Closing Secondary Databases</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
You manage secondary database opens and closes using the
|
||||
<span>
|
||||
<code class="methodname">Environment.openSecondaryDatabase()</code> method.
|
||||
</span>
|
||||
|
||||
Just as is the case with primary databases, you must provide
|
||||
<code class="methodname">Environment.openSecondaryDatabase()</code>
|
||||
|
||||
with the database's
|
||||
name and, optionally, other properties such as whether duplicate
|
||||
records are allowed, or whether the secondary database can be created on
|
||||
open. In addition, you must also provide:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>A handle to the primary database that this secondary database is
|
||||
indexing. Note that this means that secondary databases are maintained
|
||||
only for the specified <code class="classname">Database</code> handle. If you
|
||||
open the same <code class="classname">Database</code> multiple times for write
|
||||
(such as might occur when opening a database for read-only and read-write in the same application),
|
||||
then you should open the <code class="classname">SecondaryDatabase</code> for
|
||||
each such <code class="classname">Database</code> handle.</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>A <code class="classname">SecondaryConfig</code> object that provides
|
||||
properties specific to a secondary database. The most important of
|
||||
these is used to identify the key creator for the database. The key
|
||||
creator is responsible for generating keys for the secondary database.
|
||||
See <a class="xref" href="secondaryProps.html" title="Secondary Database Properties">Secondary Database Properties</a> for details.</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
|
||||
<h3 class="title">Note</h3>
|
||||
<p>
|
||||
Primary databases <span class="emphasis"><em>must not</em></span> support duplicate records.
|
||||
Secondary records point to primary records using the primary key, so that key must be unique.
|
||||
</p>
|
||||
</div>
|
||||
<p>So to open (create) a secondary database, you:</p>
|
||||
<div class="orderedlist">
|
||||
<ol type="1">
|
||||
<li>
|
||||
<p>Open your primary database.</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>Instantiate your key creator.</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>Instantiate your <code class="classname">SecondaryConfig</code> object.</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>Set your key creator object on your <code class="classname">SecondaryConfig</code>
|
||||
object.</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>Open your secondary database, specifying your primary database
|
||||
and your <code class="classname">SecondaryConfig</code> at that time.</p>
|
||||
</li>
|
||||
</ol>
|
||||
</div>
|
||||
<p>For example:</p>
|
||||
<a id="je_index1"></a>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.bind.tuple.TupleBinding;
|
||||
|
||||
import com.sleepycat.je.Database;
|
||||
import com.sleepycat.je.DatabaseConfig;
|
||||
import com.sleepycat.je.DatabaseException;
|
||||
import com.sleepycat.je.Environment;
|
||||
import com.sleepycat.je.SecondaryDatabase;
|
||||
import com.sleepycat.je.SecondaryConfig;
|
||||
|
||||
import java.io.File;
|
||||
|
||||
...
|
||||
|
||||
DatabaseConfig myDbConfig = new DatabaseConfig();
|
||||
SecondaryConfig mySecConfig = new SecondaryConfig();
|
||||
myDbConfig.setAllowCreate(true);
|
||||
mySecConfig.setAllowCreate(true);
|
||||
// Duplicates are frequently required for secondary databases.
|
||||
mySecConfig.setSortedDuplicates(true);
|
||||
|
||||
// Open the primary
|
||||
Environment myEnv = null;
|
||||
Database myDb = null;
|
||||
SecondaryDatabase mySecDb = null;
|
||||
try {
|
||||
String dbName = "myPrimaryDatabase";
|
||||
|
||||
myEnv = new Environment(new File("/tmp/JEENV"), null);
|
||||
myDb = myEnv.openDatabase(null, dbName, myDbConfig);
|
||||
|
||||
// A fake tuple binding that is not actually implemented anywhere
|
||||
// in this manual. The tuple binding is dependent on the data in use.
|
||||
// Tuple bindings are described earlier in this manual.
|
||||
TupleBinding myTupleBinding = new MyTupleBinding();
|
||||
|
||||
// Open the secondary.
|
||||
// Key creators are described in the next section.
|
||||
FullNameKeyCreator keyCreator =
|
||||
new FullNameKeyCreator(myTupleBinding);
|
||||
|
||||
// Get a secondary object and set the key creator on it.
|
||||
mySecConfig.setKeyCreator(keyCreator);
|
||||
|
||||
// Perform the actual open
|
||||
String secDbName = "mySecondaryDatabase";
|
||||
mySecDb = myEnv.openSecondaryDatabase(null, secDbName, myDb,
|
||||
mySecConfig);
|
||||
} catch (DatabaseException de) {
|
||||
// Exception handling goes here ...
|
||||
}</pre>
|
||||
<p>To close a secondary database, call its close() method. Note that
|
||||
for best results, you should close all the secondary databases associated
|
||||
with a primary database before closing the primary.</p>
|
||||
<p>For example:</p>
|
||||
<a id="je_index2"></a>
|
||||
<pre class="programlisting">try {
|
||||
if (mySecDb != null) {
|
||||
mySecDb.close();
|
||||
}
|
||||
|
||||
if (myDb != null) {
|
||||
myDb.close();
|
||||
}
|
||||
|
||||
if (myEnv != null) {
|
||||
myEnv.close();
|
||||
}
|
||||
} catch (DatabaseException dbe) {
|
||||
// Exception handling goes here
|
||||
}</pre>
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="cursorUsage.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="baseapi.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="keyCreator.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Cursor Example </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Implementing Key
|
||||
<span>Creators</span>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
483
docs/GettingStartedGuide/indexusage.html
Normal file
483
docs/GettingStartedGuide/indexusage.html
Normal file
|
|
@ -0,0 +1,483 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Secondary Database Example</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="indexes.html" title="Chapter 10. Secondary Databases" />
|
||||
<link rel="prev" href="joins.html" title="Database Joins" />
|
||||
<link rel="next" href="admin.html" title="Part III. Administering JE Applications" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Secondary Database Example</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="joins.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 10. Secondary Databases</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="admin.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="indexusage"></a>Secondary Database Example</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="toc">
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="indexusage.html#secondaryMyDbEnv">Opening Secondary Databases with
|
||||
MyDbEnv</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="indexusage.html#exampleReadSecondaries">Using Secondary Databases with ExampleInventoryRead</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</div>
|
||||
<p>In previous chapters in this book, we built applications that load
|
||||
and display several JE databases. In this example, we will extend those
|
||||
examples to use secondary databases. Specifically:</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>In <a class="xref" href="dbtUsage.html#dbenvStoredClass" title="Example 8.4 Stored Class Catalog Management with MyDbEnv">Stored Class Catalog Management with MyDbEnv</a> we built a
|
||||
class that we can use to open and manage a
|
||||
JE <code class="classname">Environment</code> and one or more <code class="classname">Database</code> objects.
|
||||
In <a class="xref" href="indexusage.html#secondaryMyDbEnv" title="Opening Secondary Databases with MyDbEnv">Opening Secondary Databases with
|
||||
MyDbEnv</a> we will extend
|
||||
that class to also open and manage a <code class="classname">SecondaryDatabase</code>.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>In <a class="xref" href="cursorUsage.html" title="Cursor Example">Cursor Example</a> we
|
||||
built an application to display our inventory database (and related
|
||||
vendor information). In <a class="xref" href="indexusage.html#exampleReadSecondaries" title="Using Secondary Databases with ExampleInventoryRead">Using Secondary Databases with ExampleInventoryRead</a> we will extend that application to
|
||||
show inventory records based on the index we cause to be loaded using
|
||||
<code class="classname">ExampleDatabasePut</code>.
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<p>
|
||||
Before we can use a secondary database, we must implement a class to extract secondary keys for us.
|
||||
We use <code class="classname">ItemNameKeyCreator</code> for this purpose.
|
||||
</p>
|
||||
<div class="example">
|
||||
<a id="ItemNameKeyCreator"></a>
|
||||
<p class="title">
|
||||
<b>Example 10.1 ItemNameKeyCreator.java</b>
|
||||
</p>
|
||||
<div class="example-contents">
|
||||
<p>
|
||||
This class assumes the primary database
|
||||
uses <code class="classname">Inventory</code> objects for the record data. The
|
||||
<code class="classname">Inventory</code> class is described in <a class="xref" href="dbtUsage.html#inventory" title="Example 8.1 Inventory.java">Inventory.java</a>.</p>
|
||||
<p>In our key creator class, we make use of a custom tuple binding
|
||||
called <code class="classname">InventoryBinding</code>. This class is described in <a class="xref" href="dbtUsage.html#InventoryBinding" title="Example 8.3 InventoryBinding.java">InventoryBinding.java</a>.</p>
|
||||
<p>You can find the following class in: </p>
|
||||
<pre class="programlisting"><span class="emphasis"><em>JE_HOME</em></span>/examples/je/gettingStarted/ItemNameKeyCreator.java</pre>
|
||||
<p>
|
||||
where <code class="literal"><span class="emphasis"><em>JE_HOME</em></span></code> is the location where you
|
||||
placed your JE distribution.
|
||||
</p>
|
||||
<a id="je_index11"></a>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.bind.tuple.TupleBinding;
|
||||
import com.sleepycat.db.SecondaryKeyCreator;
|
||||
import com.sleepycat.db.DatabaseEntry;
|
||||
import com.sleepycat.db.DatabaseException;
|
||||
import com.sleepycat.db.SecondaryDatabase;
|
||||
|
||||
public class ItemNameKeyCreator implements SecondaryKeyCreator {
|
||||
|
||||
private TupleBinding theBinding;
|
||||
|
||||
// Use the constructor to set the tuple binding
|
||||
ItemNameKeyCreator(TupleBinding binding) {
|
||||
theBinding = binding;
|
||||
}
|
||||
|
||||
// Abstract method that we must implement
|
||||
public boolean createSecondaryKey(SecondaryDatabase secDb,
|
||||
DatabaseEntry keyEntry, // From the primary
|
||||
DatabaseEntry dataEntry, // From the primary
|
||||
DatabaseEntry resultEntry) // set the key data on this.
|
||||
throws DatabaseException {
|
||||
|
||||
if (dataEntry != null) {
|
||||
// Convert dataEntry to an Inventory object
|
||||
Inventory inventoryItem =
|
||||
(Inventory)theBinding.entryToObject(dataEntry);
|
||||
// Get the item name and use that as the key
|
||||
String theItem = inventoryItem.getItemName();
|
||||
resultEntry.setData(theItem.getBytes());
|
||||
}
|
||||
return true;
|
||||
}
|
||||
} </pre>
|
||||
</div>
|
||||
</div>
|
||||
<br class="example-break" />
|
||||
<p>Now that we have a key creator, we can use it to generate keys for a secondary database. We will now extend
|
||||
<code class="classname">MyDbEnv</code> to manage a secondary database, and to use <code class="classname">ItemNameKeyCreator</code>
|
||||
to generate keys for that secondary database.
|
||||
</p>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="secondaryMyDbEnv"></a>Opening Secondary Databases with
|
||||
MyDbEnv</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>In <a class="xref" href="dbtUsage.html#dbenvStoredClass" title="Example 8.4 Stored Class Catalog Management with MyDbEnv">Stored Class Catalog Management with MyDbEnv</a> we built
|
||||
<code class="classname">MyDbEnv</code> as an example of a class that
|
||||
encapsulates <code class="classname">Environment</code> and
|
||||
<code class="classname">Database</code> opens and closes. We will now extend
|
||||
that class to manage a <code class="classname">SecondaryDatabase</code>.</p>
|
||||
<div class="example">
|
||||
<a id="mydbenvSecondary"></a>
|
||||
<p class="title">
|
||||
<b>Example 10.2 SecondaryDatabase Management with MyDbEnv</b>
|
||||
</p>
|
||||
<div class="example-contents">
|
||||
<p>We start by importing two additional classes needed to support secondary databases.
|
||||
We also add a global variable to use as a handle for our secondary database.
|
||||
</p>
|
||||
<a id="je_index12"></a>
|
||||
<pre class="programlisting">// File MyDbEnv.java
|
||||
|
||||
package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.bind.tuple.TupleBinding;
|
||||
import com.sleepycat.bind.serial.StoredClassCatalog;
|
||||
|
||||
import com.sleepycat.je.Database;
|
||||
import com.sleepycat.je.DatabaseConfig;
|
||||
import com.sleepycat.je.DatabaseException;
|
||||
import com.sleepycat.je.Environment;
|
||||
import com.sleepycat.je.EnvironmentConfig;
|
||||
<strong class="userinput"><code>import com.sleepycat.je.SecondaryConfig;</code></strong>
|
||||
<strong class="userinput"><code>import com.sleepycat.je.SecondaryDatabase;</code></strong>
|
||||
|
||||
import java.io.File;
|
||||
|
||||
public class MyDbEnv {
|
||||
|
||||
private Environment myEnv;
|
||||
|
||||
// The databases that our application uses
|
||||
private Database vendorDb;
|
||||
private Database inventoryDb;
|
||||
private Database classCatalogDb;
|
||||
<strong class="userinput"><code>private SecondaryDatabase itemNameIndexDb;</code></strong>
|
||||
|
||||
// Needed for object serialization
|
||||
private StoredClassCatalog classCatalog;
|
||||
|
||||
// Our constructor does nothing
|
||||
public MyDbEnv() {}</pre>
|
||||
<p>
|
||||
Next we update the <code class="methodname">MyDbEnv.setup()</code> method to open the
|
||||
secondary database. As a part of this, we have to pass an
|
||||
<code class="classname">ItemNameKeyCreator</code> object on the call to open the secondary
|
||||
database. Also, in order to instantiate <code class="classname">ItemNameKeyCreator</code>, we need an
|
||||
<code class="classname">InventoryBinding</code> object (we described this class in <a class="xref" href="dbtUsage.html#InventoryBinding" title="Example 8.3 InventoryBinding.java">InventoryBinding.java</a>). We do all this work together inside of
|
||||
<code class="methodname">MyDbEnv.setup()</code>.
|
||||
</p>
|
||||
<a id="je_index13"></a>
|
||||
<pre class="programlisting"> public void setup(File envHome, boolean readOnly)
|
||||
throws DatabaseException {
|
||||
|
||||
EnvironmentConfig myEnvConfig = new EnvironmentConfig();
|
||||
DatabaseConfig myDbConfig = new DatabaseConfig();
|
||||
<strong class="userinput"><code>SecondaryConfig mySecConfig = new SecondaryConfig();</code></strong>
|
||||
|
||||
// If the environment is read-only, then
|
||||
// make the databases read-only too.
|
||||
myEnvConfig.setReadOnly(readOnly);
|
||||
myDbConfig.setReadOnly(readOnly);
|
||||
<strong class="userinput"><code>mySecConfig.setReadOnly(readOnly);</code></strong>
|
||||
|
||||
// If the environment is opened for write, then we want to be
|
||||
// able to create the environment and databases if
|
||||
// they do not exist.
|
||||
myEnvConfig.setAllowCreate(!readOnly);
|
||||
myDbConfig.setAllowCreate(!readOnly);
|
||||
<strong class="userinput"><code>mySecConfig.setAllowCreate(!readOnly);</code></strong>
|
||||
|
||||
...
|
||||
// Environment and database opens omitted for brevity
|
||||
...
|
||||
|
||||
<strong class="userinput"><code>// Open the secondary database. We use this to create a
|
||||
// secondary index for the inventory database
|
||||
|
||||
// We want to maintain an index for the inventory entries based
|
||||
// on the item name. So, instantiate the appropriate key creator
|
||||
// and open a secondary database.
|
||||
ItemNameKeyCreator keyCreator =
|
||||
new ItemNameKeyCreator(new InventoryBinding());
|
||||
|
||||
// Set up the secondary properties
|
||||
mySecConfig.setAllowPopulate(true); // Allow autopopulate
|
||||
mySecConfig.setKeyCreator(keyCreator);
|
||||
// Need to allow duplicates for our secondary database
|
||||
mySecConfig.setSortedDuplicates(true);
|
||||
|
||||
// Now open it
|
||||
itemNameIndexDb =
|
||||
myEnv.openSecondaryDatabase(
|
||||
null,
|
||||
"itemNameIndex", // Index name
|
||||
inventoryDb, // Primary database handle. This is
|
||||
// the db that we're indexing.
|
||||
mySecConfig); // The secondary config</code></strong>
|
||||
} </pre>
|
||||
<p>
|
||||
Next we need an additional getter method for returning the secondary database.
|
||||
</p>
|
||||
<a id="je_index14"></a>
|
||||
<pre class="programlisting"> public SecondaryDatabase getNameIndexDB() {
|
||||
return itemNameIndexDb;
|
||||
} </pre>
|
||||
<p>Finally, we need to update the <code class="methodname">MyDbEnv.close()</code>
|
||||
method to close the new secondary database. We want to make sure that
|
||||
the secondary is closed before the primaries. While
|
||||
this is not necessary for this example because our
|
||||
closes are single-threaded, it is still a good habit to adopt.</p>
|
||||
<a id="je_index15"></a>
|
||||
<pre class="programlisting"> public void close() {
|
||||
if (myEnv != null) {
|
||||
try {
|
||||
//Close the secondary before closing the primaries
|
||||
<strong class="userinput"><code>itemNameIndexDb.close();</code></strong>
|
||||
vendorDb.close();
|
||||
inventoryDb.close();
|
||||
classCatalogDb.close();
|
||||
|
||||
// Finally, close the environment.
|
||||
myEnv.close();
|
||||
} catch(DatabaseException dbe) {
|
||||
System.err.println("Error closing MyDbEnv: " +
|
||||
dbe.toString());
|
||||
System.exit(-1);
|
||||
}
|
||||
}
|
||||
}
|
||||
} </pre>
|
||||
<p>That completes our update to <code class="classname">MyDbEnv</code>. You
|
||||
can find the complete class implementation in:
|
||||
</p>
|
||||
<pre class="programlisting"><span class="emphasis"><em>JE_HOME</em></span>/examples/je/gettingStarted/MyDbEnv.java </pre>
|
||||
<p>
|
||||
where <code class="literal"><span class="emphasis"><em>JE_HOME</em></span></code> is the location where you
|
||||
placed your JE distribution.
|
||||
</p>
|
||||
</div>
|
||||
</div>
|
||||
<br class="example-break" />
|
||||
</div>
|
||||
<p>Because we performed all our secondary database configuration management in
|
||||
<code class="classname">MyDbEnv</code>, we do not need to modify <code class="classname">ExampleDatabasePut</code> at all in
|
||||
order to create our secondary indices. When <code class="classname">ExampleDatabasePut</code> calls
|
||||
<code class="methodname">MyDbEnv.setup()</code>, all of the necessary work is performed for us.
|
||||
</p>
|
||||
<p>
|
||||
However, we still need to take advantage of the new secondary indices. We do this by updating
|
||||
<code class="classname">ExampleInventoryRead</code> to allow us to query for an inventory record based on its name.
|
||||
Remember that the primary key for an inventory record is the item's SKU. The item's name is contained in the
|
||||
<code class="classname">Inventory</code> object that is stored as each record's data in the inventory database. But
|
||||
our new secondary index now allows us to easily query based on the item's name.
|
||||
</p>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="exampleReadSecondaries"></a>Using Secondary Databases with ExampleInventoryRead</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>In the previous section we changed <code class="classname">MyDbEnv</code>
|
||||
to cause a secondary database to be built using inventory item names as
|
||||
the secondary keys. In this section, we will update
|
||||
<code class="classname">ExampleInventoryRead</code> to allow us to query our
|
||||
inventory records based on the item name. To do this, we will modify
|
||||
<code class="classname">ExampleInventoryRead</code> to accept a new command line switch,
|
||||
<code class="literal">-s</code>, whose argument is the name of an inventory item.
|
||||
If the switch is present on the command line call to
|
||||
<code class="classname">ExampleInventoryRead</code>, then the application will
|
||||
use the secondary database to look up and display all the inventory
|
||||
records with that item name. Note that we use a <code class="classname">SecondaryCursor</code>
|
||||
to seek to the item name key and then display all matching records.</p>
|
||||
<p>Remember that you can find the following class in: </p>
|
||||
<pre class="programlisting"><span class="emphasis"><em>JE_HOME</em></span>/examples/je/gettingStarted/ExampleInventoryRead.java</pre>
|
||||
<p>
|
||||
where <code class="literal"><span class="emphasis"><em>JE_HOME</em></span></code> is the location where you
|
||||
placed your JE distribution.
|
||||
</p>
|
||||
<div class="example">
|
||||
<a id="secondaryWithEIR"></a>
|
||||
<p class="title">
|
||||
<b>Example 10.3 SecondaryDatabase usage with ExampleInventoryRead</b>
|
||||
</p>
|
||||
<div class="example-contents">
|
||||
<p>First we need to import a few additional classes in order to use
|
||||
secondary databases and cursors, and then we add a single global variable:</p>
|
||||
<a id="je_index16"></a>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.je.Cursor;
|
||||
import com.sleepycat.je.Database;
|
||||
import com.sleepycat.je.DatabaseEntry;
|
||||
import com.sleepycat.je.DatabaseException;
|
||||
import com.sleepycat.je.LockMode;
|
||||
import com.sleepycat.je.OperationStatus;
|
||||
<strong class="userinput"><code>import com.sleepycat.je.SecondaryCursor;</code></strong>
|
||||
|
||||
import com.sleepycat.bind.EntryBinding;
|
||||
import com.sleepycat.bind.serial.SerialBinding;
|
||||
import com.sleepycat.bind.tuple.TupleBinding;
|
||||
|
||||
import java.io.File;
|
||||
import java.io.IOException;
|
||||
|
||||
public class ExampleInventoryRead {
|
||||
|
||||
private static File myDbEnvPath =
|
||||
new File("/tmp/JEDB");
|
||||
|
||||
// Encapsulates the database environment and databases.
|
||||
private static MyDbEnv myDbEnv = new MyDbEnv();
|
||||
|
||||
private static TupleBinding inventoryBinding;
|
||||
private static EntryBinding vendorBinding;
|
||||
|
||||
<strong class="userinput"><code>// The item to locate if the -s switch is used
|
||||
private static String locateItem;</code></strong> </pre>
|
||||
<p>Next we update <code class="methodname">ExampleInventoryRead.run()</code> to
|
||||
check to see if the <code class="literal">locateItem</code> global variable a
|
||||
value. If it does, then we show just those records related to the item
|
||||
name passed on the <code class="literal">-s</code> switch.</p>
|
||||
<a id="je_index18"></a>
|
||||
<pre class="programlisting"> private void run(String args[])
|
||||
throws DatabaseException {
|
||||
// Parse the arguments list
|
||||
parseArgs(args);
|
||||
myDbEnv.setup(myDbEnvPath, // path to the environment home
|
||||
true); // is this environment read-only?
|
||||
|
||||
// Setup our bindings.
|
||||
inventoryBinding = new InventoryBinding();
|
||||
vendorBinding =
|
||||
new SerialBinding(myDbEnv.getClassCatalog(),
|
||||
Vendor.class);
|
||||
|
||||
<strong class="userinput"><code>if (locateItem != null) {
|
||||
showItem();
|
||||
} else {</code></strong>
|
||||
showAllInventory();
|
||||
<strong class="userinput"><code>}</code></strong>
|
||||
} </pre>
|
||||
<p>
|
||||
Finally, we need to implement <code class="methodname">ExampleInventoryRead.showItem()</code>.
|
||||
This is a fairly simple method that opens a secondary cursor,
|
||||
and then displays every primary record that is related to the secondary
|
||||
key identified by the <code class="literal">locateItem</code> global variable.
|
||||
</p>
|
||||
<a id="je_index19"></a>
|
||||
<pre class="programlisting"> private void showItem() throws DatabaseException {
|
||||
SecondaryCursor secCursor = null;
|
||||
try {
|
||||
// searchKey is the key that we want to find in the
|
||||
// secondary db.
|
||||
DatabaseEntry searchKey =
|
||||
new DatabaseEntry(locateItem.getBytes("UTF-8"));
|
||||
|
||||
// foundKey and foundData are populated from the primary
|
||||
// entry that is associated with the secondary db key.
|
||||
DatabaseEntry foundKey = new DatabaseEntry();
|
||||
DatabaseEntry foundData = new DatabaseEntry();
|
||||
|
||||
// open a secondary cursor
|
||||
secCursor =
|
||||
myDbEnv.getNameIndexDB().openSecondaryCursor(null, null);
|
||||
|
||||
// Search for the secondary database entry.
|
||||
OperationStatus retVal =
|
||||
secCursor.getSearchKey(searchKey, foundKey,
|
||||
foundData, LockMode.DEFAULT);
|
||||
|
||||
// Display the entry, if one is found. Repeat until no more
|
||||
// secondary duplicate entries are found
|
||||
while(retVal == OperationStatus.SUCCESS) {
|
||||
Inventory theInventory =
|
||||
(Inventory)inventoryBinding.entryToObject(foundData);
|
||||
displayInventoryRecord(foundKey, theInventory);
|
||||
retVal = secCursor.getNextDup(searchKey, foundKey,
|
||||
foundData, LockMode.DEFAULT);
|
||||
}
|
||||
} catch (Exception e) {
|
||||
System.err.println("Error on inventory secondary cursor:");
|
||||
System.err.println(e.toString());
|
||||
e.printStackTrace();
|
||||
} finally {
|
||||
if (secCursor != null) {
|
||||
secCursor.close();
|
||||
}
|
||||
}
|
||||
}</pre>
|
||||
<p>The only other thing left to do is to update
|
||||
<code class="methodname">ExampleInventoryRead.parseArgs()</code> to support the <code class="literal">-s</code> command
|
||||
line switch. To see how this is done, see:
|
||||
</p>
|
||||
<pre class="programlisting"><span class="emphasis"><em>JE_HOME</em></span>/examples/je/gettingStarted/ExampleInventoryRead.java</pre>
|
||||
<p>
|
||||
where <code class="literal"><span class="emphasis"><em>JE_HOME</em></span></code> is the location where you
|
||||
placed your JE distribution.
|
||||
</p>
|
||||
</div>
|
||||
</div>
|
||||
<br class="example-break" />
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="joins.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="indexes.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="admin.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Database Joins </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Part III. Administering JE Applications</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
616
docs/GettingStartedGuide/introduction.html
Normal file
616
docs/GettingStartedGuide/introduction.html
Normal file
|
|
@ -0,0 +1,616 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Chapter 1. Introduction to Berkeley DB Java Edition</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="prev" href="moreinfo.html" title="For More Information" />
|
||||
<link rel="next" href="applicationoverview.html" title="The JE Application" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Chapter 1. Introduction to Berkeley DB Java Edition </th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="moreinfo.html">Prev</a> </td>
|
||||
<th width="60%" align="center"> </th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="applicationoverview.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="chapter" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title"><a id="introduction"></a>Chapter 1. Introduction to Berkeley DB Java Edition </h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="toc">
|
||||
<p>
|
||||
<b>Table of Contents</b>
|
||||
</p>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="introduction.html#features">Features</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="introduction.html#dplfeatures">DPL Features</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="introduction.html#basefeatures">Base API Features</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="introduction.html#whichapi">Which API Should You Use?</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="applicationoverview.html">The JE Application</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="applicationoverview.html#dbIntro">Database Environments</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="applicationoverview.html#key-data">Key-Data Pairs</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="applicationoverview.html#storing-intro">Storing Data</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="applicationoverview.html#duplicatesintro">Duplicate Data</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="applicationoverview.html#replacedeleteIntro">Replacing and Deleting Entries</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="applicationoverview.html#secondary">Secondary Keys</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="applicationoverview.html#transactionIntro">Transactions</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="applicationoverview.html#resourcesIntro">JE Resources</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="applicationoverview.html#applicationConsiderations">
|
||||
Application Considerations
|
||||
</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="restore.html">JE Backup and Restore</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="jca.html">JCA Support</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="jmx.html">JConsole and JMX Support</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="gettingit.html">Getting and Using JE </a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="jeexceptions.html">JE Exceptions</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="logfilesrevealed.html">Six Things Everyone Should Know about JE Log Files</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</div>
|
||||
<p>
|
||||
Welcome to Berkeley DB Java Edition (JE). JE is a general-purpose,
|
||||
transaction-protected, embedded database written in 100% Java (JE
|
||||
makes no JNI calls). As such, it offers the Java developer safe and
|
||||
efficient in-process storage and management of arbitrary data.
|
||||
</p>
|
||||
<p>
|
||||
You use JE through a series of Java APIs which give you the
|
||||
ability to read and write your data, manage your database(s), and
|
||||
perform other more advanced activities such as managing
|
||||
transactions. The Java APIs that you use to interact with JE
|
||||
come in two basic flavors. The first is a high-level API that
|
||||
allows you to make Java classes persistent. The second is a
|
||||
lower-level API which provides additional flexibility when interacting
|
||||
with JE databases.
|
||||
</p>
|
||||
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
|
||||
<h3 class="title">Note</h3>
|
||||
<p>
|
||||
For long-time users of JE, the lower-level API is the
|
||||
traditional API that you are probably accustomed to using.
|
||||
</p>
|
||||
</div>
|
||||
<p>
|
||||
Regardless of the API set that you choose to use, there are a
|
||||
series of concepts and APIs that are common across the product.
|
||||
This manual starts by providing a high-level examination of
|
||||
JE. It then describes the APIs you use regardless of the API
|
||||
set that you choose to use. It then provides information on using the
|
||||
Direct Persistence Layer (DPL) API, followed by information on using
|
||||
the more extensive "base" API. Finally, we provide some database
|
||||
administration information.
|
||||
</p>
|
||||
<p>
|
||||
Note that the information provided here is intended to focus on
|
||||
only introductory API usage. Other books describe more advanced
|
||||
topics, such as transactional usage. See the <a class="xref" href="moreinfo.html" title="For More Information">For More Information</a> section for
|
||||
a listing of other titles in the JE documentation set.
|
||||
</p>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="features"></a>Features</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="toc">
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="introduction.html#dplfeatures">DPL Features</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="introduction.html#basefeatures">Base API Features</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="introduction.html#whichapi">Which API Should You Use?</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</div>
|
||||
<p>
|
||||
JE provides an enterprise-class Java-based data management
|
||||
solution. All you need to get started is to add a single jar file to your
|
||||
application's classpath. See <a class="xref" href="gettingit.html" title="Getting and Using JE">Getting and Using JE </a> for more information.
|
||||
</p>
|
||||
<p>
|
||||
JE offers the following major features:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
Large database support. JE databases efficiently scale
|
||||
from one to millions of records. The size of your JE
|
||||
databases are likely to be limited more by hardware resources
|
||||
than by any limits imposed upon you by JE.
|
||||
</p>
|
||||
<p>
|
||||
Databases are described in
|
||||
<a class="xref" href="databases.html" title="Chapter 7. Databases">Databases</a>.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Database environments. Database environments provide
|
||||
a unit of encapsulation and management for one or
|
||||
more databases. Environments are also the
|
||||
unit of management for internal resources such as the
|
||||
in-memory cache and the background threads.
|
||||
Finally, you use environments to manage concurrency and
|
||||
transactions. Note that all applications using JE
|
||||
are required to use database environments.
|
||||
</p>
|
||||
<p>
|
||||
Database environments are described in
|
||||
<a class="xref" href="env.html" title="Chapter 2. Database Environments">Database Environments</a>.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Multiple thread and process support. JE is designed for
|
||||
multiple threads of control. Both read and write operations
|
||||
can be performed by multiple threads. JE uses record-level
|
||||
locking for high concurrency in threaded applications.
|
||||
Further, JE uses timeouts for deadlock detection to help
|
||||
you ensure that two threads of control do not deadlock
|
||||
indefinitely.
|
||||
</p>
|
||||
<p>
|
||||
Moreover, JE allows multiple processes to access the same
|
||||
databases. However, in this configuration JE requires that
|
||||
there be no more than one process allowed to write to the
|
||||
database. Read-only processes are guaranteed a consistent,
|
||||
although potentially out of date, view of the stored data as of
|
||||
the time that the environment is opened.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>Transactions. Transactions allow you to treat one or more
|
||||
operations on one or more databases as a single unit of work.
|
||||
JE transactions offer the application developer recoverability, atomicity, and
|
||||
isolation for your database operations.
|
||||
</p>
|
||||
<p>Note that transaction protection is optional. Transactions are
|
||||
described in the <em class="citetitle">Berkeley DB, Java Edition Getting Started with Transaction Processing</em> guide.</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
In-memory cache. The cache allows for high speed
|
||||
database access for both read and write operations by
|
||||
avoiding unnecessary disk I/O. The cache will grow
|
||||
on demand up to a pre-configured maximum size. To
|
||||
improve your application's performance immediately
|
||||
after startup time, you can preload your cache in
|
||||
order to avoid disk I/O for production requests of
|
||||
your data.
|
||||
</p>
|
||||
<p>
|
||||
Cache management is described in
|
||||
<a class="xref" href="cachesize.html" title="Sizing the Cache">Sizing the Cache</a>.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
|
||||
Indexes. JE allows you to easily create and maintain
|
||||
secondary indices for your primary data. In this way, you can obtain rapid
|
||||
access to your data through the use of an alternative, or
|
||||
secondary, key.
|
||||
</p>
|
||||
<p>
|
||||
How indices work is dependent upon the API you are
|
||||
using. If you are using the DPL, see
|
||||
<a class="xref" href="persist_index.html" title="Chapter 4. Working with Indices">Working with Indices</a>.
|
||||
Otherwise, see
|
||||
<a class="xref" href="indexes.html" title="Chapter 10. Secondary Databases">Secondary Databases</a>.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Log files. JE databases are stored in one
|
||||
or more numerically-named log files in the environment
|
||||
directory. The log files are write-once and are
|
||||
portable across platforms with different endian-ness.
|
||||
</p>
|
||||
<p>
|
||||
Unlike other database implementations, there is no
|
||||
distinction between database files (that is, the "material
|
||||
database") and log files. Instead JE employs a log-based storage
|
||||
system to protect database modifications. Before any
|
||||
change is made to a database, JE writes information about the
|
||||
change to the log file.
|
||||
</p>
|
||||
<p>
|
||||
Note that JE's log files are not binary compatible with Berkeley
|
||||
DB's database files. However, both products provide dump and load
|
||||
utilities, and the files that these operate on are compatible across
|
||||
product lines.
|
||||
</p>
|
||||
<p>
|
||||
JE's log files are described in more detail in
|
||||
<a class="xref" href="backuprestore.html" title="Chapter 11. Backing up and Restoring Berkeley DB Java Edition Applications">Backing up and Restoring Berkeley DB Java Edition Applications</a>.
|
||||
For information on using JE's dump and load utilities,
|
||||
see <a class="xref" href="commandlinetools.html" title="The Command Line Tools">The Command Line Tools</a>.
|
||||
Finally, for a short list of things to know about log files while you are learning JE,
|
||||
see <a class="xref" href="logfilesrevealed.html" title="Six Things Everyone Should Know about JE Log Files">Six Things Everyone Should Know about JE Log Files</a>.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Background threads. JE provides several threads
|
||||
that manage internal resources for you. The
|
||||
checkpointer is responsible for flushing database
|
||||
data to disk that was written to cache as the result
|
||||
of a transaction commit (this is done in order to
|
||||
shorten recovery time). The compressor thread
|
||||
removes subtrees from the database that are empty
|
||||
because of deletion activity. Finally, the cleaner
|
||||
thread is responsible for cleaning and removing
|
||||
unneeded log files, thereby helping you to save on
|
||||
disk space.
|
||||
</p>
|
||||
<p>
|
||||
Background thread management is described in
|
||||
<a class="xref" href="backgroundthreads.html" title="Managing the Background Threads">Managing the Background Threads</a>.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
|
||||
Backup and restore. JE's backup procedure
|
||||
consists of simply copying JE's log files to a
|
||||
safe location for storage. To recover from a
|
||||
catastrophic failure, you copy your archived log
|
||||
files back to your production location on disk and
|
||||
reopen the JE environment.
|
||||
</p>
|
||||
<p>
|
||||
|
||||
Note that JE always performs <span class="emphasis"><em>normal
|
||||
recovery</em></span> when it opens a database
|
||||
environment. Normal recovery brings the database to a
|
||||
consistent state based on change information found in
|
||||
the database log files.
|
||||
|
||||
</p>
|
||||
<p>
|
||||
JE's backup and recovery mechanisms are described in
|
||||
<a class="xref" href="backuprestore.html" title="Chapter 11. Backing up and Restoring Berkeley DB Java Edition Applications">Backing up and Restoring Berkeley DB Java Edition Applications</a>.
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="dplfeatures"></a>DPL Features</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
The DPL is one of two APIs that JE provides for
|
||||
interaction with JE databases. The DPL provides
|
||||
the ability to cause any Java type to be persistent
|
||||
without implementing special interfaces. The
|
||||
only real requirement is that each persistent
|
||||
class have a default constructor.
|
||||
</p>
|
||||
<p>
|
||||
The DPL provides all of the features previously identified
|
||||
in this chapter. In addition, the DPL offers you:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
A type safe, convenient way to access
|
||||
persistent objects.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
No hand-coding of bindings is required.
|
||||
A binding is a way of transforming data
|
||||
types into a format which can be stored
|
||||
in a JE database. If you do not use
|
||||
the DPL, you may be required to
|
||||
create custom bindings for your data
|
||||
types.
|
||||
</p>
|
||||
<p>
|
||||
See <a class="xref" href="bindAPI.html" title="Using the BIND APIs">Using the BIND APIs</a>
|
||||
for more information on creating data bindings.
|
||||
</p>
|
||||
<p>
|
||||
Note that Java byte code enhancement is
|
||||
used by the DPL API to provide fully
|
||||
optimized bindings that do not use Java
|
||||
reflection.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
No external schema is required to define
|
||||
primary and secondary index keys. Java
|
||||
annotations are used to define all
|
||||
metadata.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Interoperability with external components is
|
||||
supported using the Java collections framework.
|
||||
Any index can be accessed using a standard
|
||||
<code class="literal">java.util</code> collection.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Class evolution is explicitly supported. This
|
||||
means you can add fields or widen types
|
||||
automatically and transparently.
|
||||
</p>
|
||||
<p>
|
||||
You can also perform many incompatible class
|
||||
changes, such as renaming fields or refactoring a
|
||||
single class. This is done using a built-in
|
||||
DPL mechanism called
|
||||
<span class="emphasis"><em>mutations</em></span>.
|
||||
Mutations are automatically applied as data is
|
||||
accessed so as to avoid downtime to convert large
|
||||
databases during a software upgrade.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Persistent class fields can be private,
|
||||
package-private, protected or public. The
|
||||
DPL can access persistence fields
|
||||
either by bytecode enhancement or by reflection.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
The performance of the underlying JE
|
||||
engine is safe-guarded. All
|
||||
DPL operations are mapped directly to
|
||||
the underlying APIs, object bindings are
|
||||
lightweight, and all engine tuning parameters are
|
||||
available.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Java 1.5 generic types and annotations are
|
||||
supported.
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="basefeatures"></a>Base API Features</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
If you are not using the DPL, then the following concepts and
|
||||
features are likely to be of interest to you:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
Database records. All database records are organized
|
||||
as simple key/data pairs. Both keys and data can be
|
||||
anything from primitive Java types to the most
|
||||
complex of Java objects.
|
||||
</p>
|
||||
<p>
|
||||
Database records are described in
|
||||
<a class="xref" href="DBEntry.html" title="Chapter 8. Database Records">Database Records</a>.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Direct database read and write. You can use methods
|
||||
of a <code class="classname">Database</code> object to read
|
||||
and write database records. Reading and writing using
|
||||
<code class="classname">Database</code> objects are described
|
||||
in
|
||||
<a class="xref" href="DBEntry.html" title="Chapter 8. Database Records">Database Records</a>.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Cursors. Cursors give you the ability to sequentially
|
||||
move through a database. Using cursors, you can seek
|
||||
to a specific point in the database (using search
|
||||
criteria applied to the key and/or the data portion
|
||||
of a database record) and then either step forward or
|
||||
step backwards through the database.
|
||||
</p>
|
||||
<p>
|
||||
Cursors are described in detail in
|
||||
<a class="xref" href="Cursors.html" title="Chapter 9. Using Cursors">Using Cursors</a>.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
JCA. JE provides support for the Java Connector Architecture. See
|
||||
<a class="xref" href="jca.html" title="JCA Support">JCA Support</a> for more information.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
JMX. JE provides support for Java Management Extensions.
|
||||
See <a class="xref" href="jmx.html" title="JConsole and JMX Support">JConsole and JMX Support</a> for more information.
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="whichapi"></a>Which API Should You Use?</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
Of the two APIs that JE makes available to you, we
|
||||
recommend that you use the DPL if all
|
||||
you want to do is make classes with a relatively static schema to
|
||||
be persistent.
|
||||
</p>
|
||||
<p>
|
||||
Further, if you are porting an application between Berkley DB
|
||||
and Berkeley DB Java Edition, then you should not use the DPL as the
|
||||
base API is a much closer match to the Berkley DB Java API.
|
||||
</p>
|
||||
<p>
|
||||
Additionally, if your application uses a highly dynamic
|
||||
schema, then the DPL is probably a poor choice for
|
||||
your application, although the use of Java annotations
|
||||
can make the DPL work a little better for you in this
|
||||
situation.
|
||||
</p>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="moreinfo.html">Prev</a> </td>
|
||||
<td width="20%" align="center"> </td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="applicationoverview.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">For More Information </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> The JE Application</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
148
docs/GettingStartedGuide/inventoryclass.html
Normal file
148
docs/GettingStartedGuide/inventoryclass.html
Normal file
|
|
@ -0,0 +1,148 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Inventory.java</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="dpl_example.html" title="Chapter 6. A DPL Example" />
|
||||
<link rel="prev" href="dpl_example.html" title="Chapter 6. A DPL Example" />
|
||||
<link rel="next" href="mydbenv-persist.html" title="MyDbEnv" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Inventory.java</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="dpl_example.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 6. A DPL Example</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="mydbenv-persist.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="inventoryclass"></a>Inventory.java</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
Our example's <code class="classname">Inventory</code>
|
||||
class is much like our <code class="classname">Vendor</code>
|
||||
class in that it is simply used to encapsulate
|
||||
data. However, in this case we want to be able
|
||||
to access objects two different ways: by
|
||||
product SKU and by product name.
|
||||
</p>
|
||||
<p>
|
||||
In our data set, the product SKU is required to be
|
||||
unique, so we use that as the primary key. The
|
||||
product name, however, is not a unique value so we
|
||||
set this up as a secondary key.
|
||||
</p>
|
||||
<p>
|
||||
The class appears as follows in our example:
|
||||
</p>
|
||||
<pre class="programlisting">package persist.gettingStarted;
|
||||
|
||||
import com.sleepycat.persist.model.Entity;
|
||||
import com.sleepycat.persist.model.PrimaryKey;
|
||||
import static com.sleepycat.persist.model.Relationship.*;
|
||||
import com.sleepycat.persist.model.SecondaryKey;
|
||||
|
||||
@Entity
|
||||
public class Inventory {
|
||||
|
||||
// Primary key is sku
|
||||
@PrimaryKey
|
||||
private String sku;
|
||||
|
||||
// Secondary key is the itemName
|
||||
@SecondaryKey(relate=MANY_TO_ONE)
|
||||
private String itemName;
|
||||
|
||||
private String category;
|
||||
private String vendor;
|
||||
private int vendorInventory;
|
||||
private float vendorPrice;
|
||||
|
||||
public void setSku(String data) {
|
||||
sku = data;
|
||||
}
|
||||
|
||||
public void setItemName(String data) {
|
||||
itemName = data;
|
||||
}
|
||||
|
||||
public void setCategory(String data) {
|
||||
category = data;
|
||||
}
|
||||
|
||||
public void setVendorInventory(int data) {
|
||||
vendorInventory = data;
|
||||
}
|
||||
|
||||
public void setVendor(String data) {
|
||||
vendor = data;
|
||||
}
|
||||
|
||||
public void setVendorPrice(float data) {
|
||||
vendorPrice = data;
|
||||
}
|
||||
|
||||
public String getSku() {
|
||||
return sku;
|
||||
}
|
||||
|
||||
public String getItemName() {
|
||||
return itemName;
|
||||
}
|
||||
|
||||
public String getCategory() {
|
||||
return category;
|
||||
}
|
||||
|
||||
public int getVendorInventory() {
|
||||
return vendorInventory;
|
||||
}
|
||||
|
||||
public String getVendor() {
|
||||
return vendor;
|
||||
}
|
||||
|
||||
public float getVendorPrice() {
|
||||
return vendorPrice;
|
||||
}
|
||||
} </pre>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="dpl_example.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="dpl_example.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="mydbenv-persist.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Chapter 6. A DPL Example </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> MyDbEnv</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
106
docs/GettingStartedGuide/jca.html
Normal file
106
docs/GettingStartedGuide/jca.html
Normal file
|
|
@ -0,0 +1,106 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>JCA Support</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="introduction.html" title="Chapter 1. Introduction to Berkeley DB Java Edition" />
|
||||
<link rel="prev" href="restore.html" title="JE Backup and Restore" />
|
||||
<link rel="next" href="jmx.html" title="JConsole and JMX Support" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">JCA Support</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="restore.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 1. Introduction to Berkeley DB Java Edition </th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="jmx.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="jca"></a>JCA Support</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
<span class="emphasis"><em>JCA</em></span> is the <span class="emphasis"><em>Java Connector Architecture</em></span>. This architecture provides a standard for connecting
|
||||
the J2EE platform to legacy enterprise information systems (EIS), such as ERP systems, database systems, and
|
||||
legacy applications not written in Java. JE supports this architecture.
|
||||
</p>
|
||||
<p>
|
||||
Users who want to run JE within a J2EE Application Server can use the JCA Resource Adapter to connect to
|
||||
JE through a standard API. Note that the base API is required if you want to do this.
|
||||
The JE Resource Adapter supports all three J2EE application server transaction
|
||||
types:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
No transaction.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Local transactions.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
XA transactions.
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<p>
|
||||
JCA also includes the Java Transaction API (JTA), which means that JE supports 2 phase commit (XA).
|
||||
Therefore, JEs can participate in distributed transactions managed by either a J2EE server or the
|
||||
applications direct use of the JTA API.
|
||||
</p>
|
||||
<p>
|
||||
The JE distribution includes an example showing JCA usage in a simple EJB. The Resource Adaptor has been
|
||||
tested using JBoss 3.2.6, and the Sun Java System Application Server, version 8.1. Instructions for how to build
|
||||
the Resource Adapter and run a simple "smoke test" example for each of the application servers can be found
|
||||
here:
|
||||
</p>
|
||||
<pre class="programlisting"><span class="emphasis"><em>JE_HOME</em></span>/examples/jca/HOWTO-jboss.txt</pre>
|
||||
<p>
|
||||
and
|
||||
</p>
|
||||
<pre class="programlisting"><span class="emphasis"><em>JE_HOME</em></span>/examples/jca/HOWTO-sjsas.txt</pre>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="restore.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="introduction.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="jmx.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">JE Backup and Restore </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> JConsole and JMX Support</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
154
docs/GettingStartedGuide/jeexceptions.html
Normal file
154
docs/GettingStartedGuide/jeexceptions.html
Normal file
|
|
@ -0,0 +1,154 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>JE Exceptions</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="introduction.html" title="Chapter 1. Introduction to Berkeley DB Java Edition" />
|
||||
<link rel="prev" href="gettingit.html" title="Getting and Using JE" />
|
||||
<link rel="next" href="logfilesrevealed.html" title="Six Things Everyone Should Know about JE Log Files" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">JE Exceptions</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="gettingit.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 1. Introduction to Berkeley DB Java Edition </th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="logfilesrevealed.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="jeexceptions"></a>JE Exceptions</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
Before describing the Java API usage, it is first useful to examine the
|
||||
exceptions thrown by those APIs. So, briefly, this section describes the
|
||||
exceptions that you can generally expect to encounter when writing JE
|
||||
applications. This list is not definitive. Exceptions beyond these can be
|
||||
expected, depending on the specific database activity you are performing.
|
||||
See the Javadoc for more information.
|
||||
</p>
|
||||
<p>
|
||||
All of the JE APIs throw
|
||||
<code class="classname">DatabaseException</code>.
|
||||
<a class="ulink" href="../java/com/sleepycat/je/DatabaseException.html" target="_top">DatabaseException</a> extends
|
||||
<code class="classname">java.lang.Exception</code>. Also, the following
|
||||
classes are subclasses of <code class="classname">DatabaseException</code>:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
<a class="ulink" href="../java/com/sleepycat/je/DatabaseNotFoundException.html" target="_top">DatabaseNotFoundException</a>
|
||||
</p>
|
||||
<p>
|
||||
Thrown whenever an operation requires a database, and that
|
||||
database cannot be found.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<a class="ulink" href="../java/com/sleepycat/je/DiskLimitException.html" target="_top">DiskLimitException</a>
|
||||
</p>
|
||||
<p>
|
||||
Indicates that you have reached your disk usage thresholds. Writes are
|
||||
no longer allowed when these thresholds are exceeded. The thresholds
|
||||
are set using the <a class="ulink" href="../java/com/sleepycat/je/EnvironmentConfig.html#MAX_DISK" target="_top">EnvironmentConfig.MAX_DISK</a> and <a class="ulink" href="../java/com/sleepycat/je/EnvironmentConfig.html#FREE_DISK" target="_top">EnvironmentConfig.FREE_DISK</a> properties. This exception
|
||||
can be thrown as the result of any write operation, including database
|
||||
record writes, checkpoints, and database and environment syncs.
|
||||
</p>
|
||||
<p>
|
||||
When closing the environment, this exception can be seen.
|
||||
However, the environment will still be properly closed.
|
||||
</p>
|
||||
<p>
|
||||
For information on setting these properties, see
|
||||
<a class="xref" href="diskthreshold.html" title="Setting Disk Thresholds">Setting Disk Thresholds</a>.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<a class="ulink" href="../java/com/sleepycat/je/EnvironmentFailureException.html" target="_top">EnvironmentFailureException</a>
|
||||
</p>
|
||||
<p>
|
||||
Indicates that a failure has occurred that could impact the Environment as
|
||||
a whole. Depending on the nature of the failure, this exception might
|
||||
indicate that <a class="ulink" href="../java/com/sleepycat/je/Environment.html#close--" target="_top">Environment.close()</a> should
|
||||
be called. Use <a class="ulink" href="../java/com/sleepycat/je/Environment.html#isValid--" target="_top">Environment.isValid()</a> to
|
||||
determine if all <a class="ulink" href="../java/com/sleepycat/je/Environment.html" target="_top">Environment</a> handles must
|
||||
be reopened. If <code class="literal">true</code>, the environment can
|
||||
continue operating without being reopened.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<a class="ulink" href="../java/com/sleepycat/je/LockConflictException.html" target="_top">LockConflictException</a>
|
||||
</p>
|
||||
<p>
|
||||
The common base class for all exceptions that result from record
|
||||
lock conflicts. Upon receiving this exception, any open cursors
|
||||
must be closed, the enclosing transaction aborted and,
|
||||
optionally, the transaction retried. Transactions are described
|
||||
in the <em class="citetitle">Berkeley DB, Java Edition Getting Started with Transaction Processing</em> guide.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<a class="ulink" href="../java/com/sleepycat/je/LogWriteException.html" target="_top">LogWriteException</a>
|
||||
</p>
|
||||
<p>
|
||||
Thrown when an <code class="classname">IOException</code> or other failure occurs
|
||||
when writing to the JE log. This exception might be indicative of a
|
||||
full disk, although an <code class="classname">IOException</code> does not contain
|
||||
enough information to determine this definitively.
|
||||
</p>
|
||||
<p>
|
||||
This exception can be thrown as the result of any write
|
||||
operation, including database record writes, checkpoints, and
|
||||
database and environment syncs.
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<p>
|
||||
Note that <code class="classname">DatabaseException</code> and its subclasses belong to the
|
||||
<code class="literal">com.sleepycat.je</code> package.
|
||||
</p>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="gettingit.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="introduction.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="logfilesrevealed.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Getting and Using JE </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Six Things Everyone Should Know about JE Log Files</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
74
docs/GettingStartedGuide/jmx.html
Normal file
74
docs/GettingStartedGuide/jmx.html
Normal file
|
|
@ -0,0 +1,74 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>JConsole and JMX Support</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="introduction.html" title="Chapter 1. Introduction to Berkeley DB Java Edition" />
|
||||
<link rel="prev" href="jca.html" title="JCA Support" />
|
||||
<link rel="next" href="gettingit.html" title="Getting and Using JE" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">JConsole and JMX Support</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="jca.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 1. Introduction to Berkeley DB Java Edition </th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="gettingit.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="jmx"></a>JConsole and JMX Support</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
<span class="emphasis"><em>JMX</em></span> is the <span class="emphasis"><em>Java Management Extensions</em></span>. This extension provides
|
||||
tools for managing and monitoring devices, applications, and service-driven networks. JE supports this extension.
|
||||
</p>
|
||||
<p>
|
||||
The JE distribution supplies MBeans that can be deployed for monitoring a JE environment in any JMX
|
||||
server (such as an J2EE application server). Statistics and key operations can be invoked from these MBeans.
|
||||
In addition, JE provides a plugin for the <span class="emphasis"><em>jconsole</em></span> utility which
|
||||
lets the user graphically access this information.
|
||||
</p>
|
||||
<p>
|
||||
For information on how to use the <span class="emphasis"><em>jconsole</em></span> plugin see:
|
||||
</p>
|
||||
<pre class="programlisting"><span class="emphasis"><em>JE_HOME</em></span>/docs/jconsole/JConsole-plugin.html</pre>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="jca.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="introduction.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="gettingit.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">JCA Support </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Getting and Using JE </td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
377
docs/GettingStartedGuide/joins.html
Normal file
377
docs/GettingStartedGuide/joins.html
Normal file
|
|
@ -0,0 +1,377 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Database Joins</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="indexes.html" title="Chapter 10. Secondary Databases" />
|
||||
<link rel="prev" href="secondaryCursor.html" title="Using Secondary Cursors" />
|
||||
<link rel="next" href="indexusage.html" title="Secondary Database Example" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Database Joins</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="secondaryCursor.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 10. Secondary Databases</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="indexusage.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="joins"></a>Database Joins</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="toc">
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="joins.html#joinUsage">Using Join Cursors</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="joins.html#joinconfig">JoinCursor Properties</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</div>
|
||||
<p>
|
||||
If you have two or more secondary databases associated with a primary
|
||||
database, then you can retrieve primary records based on the intersection of
|
||||
multiple secondary entries. You do this using a
|
||||
<span><code class="classname">JoinCursor</code>.</span>
|
||||
|
||||
</p>
|
||||
<p>
|
||||
Throughout this document we have presented a
|
||||
<span>class</span>
|
||||
|
||||
that stores
|
||||
<span>inventory</span>
|
||||
information on grocery
|
||||
<span>items.</span>
|
||||
|
||||
That
|
||||
<span>class</span>
|
||||
|
||||
is fairly simple with a limited
|
||||
number of data members, few of which would be interesting from a query
|
||||
perspective. But suppose, instead, that we were storing
|
||||
information on something with many more characteristics that can be queried, such
|
||||
as an automobile. In that case, you may be storing information such as
|
||||
color, number of doors, fuel mileage, automobile type, number of
|
||||
passengers, make, model, and year, to name just a few.
|
||||
</p>
|
||||
<p>
|
||||
In this case, you would still likely be using some unique value to key your
|
||||
primary entries (in the United States, the automobile's VIN would be
|
||||
ideal for this purpose). You would then create a
|
||||
<span>class</span>
|
||||
|
||||
that identifies
|
||||
all the characteristics of the automobiles in your inventory.
|
||||
|
||||
<span>
|
||||
You would
|
||||
also have to create some mechanism by which you would move instances of
|
||||
this class in and out of Java <code class="literal">byte</code> arrays. We
|
||||
described the concepts and mechanisms by which you can perform these
|
||||
activities in <a class="xref" href="DBEntry.html" title="Chapter 8. Database Records">Database Records</a>.
|
||||
</span>
|
||||
</p>
|
||||
<p>
|
||||
To query this data, you might then create multiple secondary databases,
|
||||
one for each of the characteristics that you want to query. For
|
||||
example, you might create a secondary for color, another for number of
|
||||
doors, another for number of passengers, and so forth. Of course, you
|
||||
will need a unique
|
||||
<span>key creator</span>
|
||||
|
||||
for each such secondary database. You do
|
||||
all of this using the concepts and techniques described throughout this
|
||||
chapter.
|
||||
</p>
|
||||
<p>
|
||||
Once you have created this primary database and all interesting
|
||||
secondaries, what you have is the ability to retrieve automobile records
|
||||
based on a single characteristic. You can, for example, find all the
|
||||
automobiles that are red. Or you can find all the automobiles that have
|
||||
four doors. Or all the automobiles that are minivans.
|
||||
</p>
|
||||
<p>
|
||||
The next most natural step, then, is to form compound queries, or joins.
|
||||
For example, you might want to find all the automobiles that are red,
|
||||
and that were built by Toyota, and that are minivans. You can do this
|
||||
using a
|
||||
<span><code class="classname">JoinCursor</code> class instance.</span>
|
||||
|
||||
</p>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="joinUsage"></a>Using Join Cursors</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
To use a join cursor:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
Open two or more
|
||||
<span>secondary cursors. These </span>
|
||||
cursors
|
||||
<span>must be obtained from</span>
|
||||
|
||||
secondary databases that are associated with
|
||||
the same primary database.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Position each such cursor to the secondary key
|
||||
value in which you are interested. For example, to build on
|
||||
the previous description, the cursor for the color
|
||||
database is positioned to the <code class="literal">red</code> records
|
||||
while the cursor for the model database is positioned to the
|
||||
<code class="literal">minivan</code> records, and the cursor for the
|
||||
make database is positioned to <code class="literal">Toyota</code>.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
|
||||
Create an array of <span>secondary</span> cursors, and
|
||||
place in it each of the cursors that are participating in your join query.
|
||||
|
||||
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
|
||||
Obtain a join cursor. You do this using the
|
||||
<code class="methodname">Database.join()</code>
|
||||
|
||||
|
||||
method. You must pass this method the array of secondary cursors that you
|
||||
opened and positioned in the previous steps.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Iterate over the set of matching records
|
||||
<span>using <code class="methodname">JoinCursor.getNext()</code></span>
|
||||
until
|
||||
<span><code class="classname">OperationStatus</code> is not <code class="literal">SUCCESS</code>.</span>
|
||||
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Close your <span>join</span> cursor.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
If you are done with them, close all your <span>secondary</span> cursors.
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<p>
|
||||
For example:
|
||||
</p>
|
||||
<a id="je_index9"></a>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.je.Database;
|
||||
import com.sleepycat.je.DatabaseEntry;
|
||||
import com.sleepycat.je.DatabaseException;
|
||||
import com.sleepycat.je.JoinCursor;
|
||||
import com.sleepycat.je.LockMode;
|
||||
import com.sleepycat.je.OperationStatus;
|
||||
import com.sleepycat.je.SecondaryCursor;
|
||||
import com.sleepycat.je.SecondaryDatabase;
|
||||
|
||||
...
|
||||
|
||||
// Database and secondary database opens omitted for brevity.
|
||||
// Assume a primary database handle:
|
||||
// automotiveDB
|
||||
// Assume 3 secondary database handles:
|
||||
// automotiveColorDB -- index based on automobile color
|
||||
// automotiveTypeDB -- index based on automobile type
|
||||
// automotiveMakeDB -- index based on the manufacturer
|
||||
|
||||
// Query strings:
|
||||
String theColor = "red";
|
||||
String theType = "minivan";
|
||||
String theMake = "Toyota";
|
||||
|
||||
// Secondary cursors used for the query:
|
||||
SecondaryCursor colorSecCursor = null;
|
||||
SecondaryCursor typeSecCursor = null;
|
||||
SecondaryCursor makeSecCursor = null;
|
||||
|
||||
// The join cursor
|
||||
JoinCursor joinCursor = null;
|
||||
|
||||
// These are needed for our queries
|
||||
DatabaseEntry foundKey = new DatabaseEntry();
|
||||
DatabaseEntry foundData = new DatabaseEntry();
|
||||
|
||||
// All cursor operations are enclosed in a try block to ensure that they
|
||||
// get closed in the event of an exception.
|
||||
|
||||
try {
|
||||
// Database entries used for the query:
|
||||
DatabaseEntry color = new DatabaseEntry(theColor.getBytes("UTF-8"));
|
||||
DatabaseEntry type = new DatabaseEntry(theType.getBytes("UTF-8"));
|
||||
DatabaseEntry make = new DatabaseEntry(theMake.getBytes("UTF-8"));
|
||||
|
||||
colorSecCursor = automotiveColorDB.openSecondaryCursor(null, null);
|
||||
typeSecCursor = automotiveTypeDB.openSecondaryCursor(null, null);
|
||||
makeSecCursor = automotiveMakeDB.openSecondaryCursor(null, null);
|
||||
|
||||
// Position all our secondary cursors to our query values.
|
||||
OperationStatus colorRet =
|
||||
colorSecCursor.getSearchKey(color, foundData, LockMode.DEFAULT);
|
||||
OperationStatus typeRet =
|
||||
typeSecCursor.getSearchKey(type, foundData, LockMode.DEFAULT);
|
||||
OperationStatus makeRet =
|
||||
makeSecCursor.getSearchKey(make, foundData, LockMode.DEFAULT);
|
||||
|
||||
// If all our searches returned successfully, we can proceed
|
||||
if (colorRet == OperationStatus.SUCCESS &&
|
||||
typeRet == OperationStatus.SUCCESS &&
|
||||
makeRet == OperationStatus.SUCCESS) {
|
||||
|
||||
// Get a secondary cursor array and populate it with our
|
||||
// positioned cursors
|
||||
SecondaryCursor[] cursorArray = {colorSecCursor,
|
||||
typeSecCursor,
|
||||
makeSecCursor};
|
||||
|
||||
// Create the join cursor
|
||||
joinCursor = automotiveDB.join(cursorArray, null);
|
||||
|
||||
// Now iterate over the results, handling each in turn
|
||||
while (joinCursor.getNext(foundKey, foundData, LockMode.DEFAULT) ==
|
||||
OperationStatus.SUCCESS) {
|
||||
|
||||
// Do something with the key and data retrieved in
|
||||
// foundKey and foundData
|
||||
}
|
||||
}
|
||||
} catch (DatabaseException dbe) {
|
||||
// Error reporting goes here
|
||||
} catch (Exception e) {
|
||||
// Error reporting goes here
|
||||
} finally {
|
||||
try {
|
||||
// Make sure to close out all our cursors
|
||||
if (colorSecCursor != null) {
|
||||
colorSecCursor.close();
|
||||
}
|
||||
if (typeSecCursor != null) {
|
||||
typeSecCursor.close();
|
||||
}
|
||||
if (makeSecCursor != null) {
|
||||
makeSecCursor.close();
|
||||
}
|
||||
if (joinCursor != null) {
|
||||
joinCursor.close();
|
||||
}
|
||||
} catch (DatabaseException dbe) {
|
||||
// Error reporting goes here
|
||||
}
|
||||
} </pre>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="joinconfig"></a>JoinCursor Properties</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
You can set <code class="classname">JoinCursor</code> properties using the
|
||||
<code class="classname">JoinConfig</code> class. Currently there is just one property that you can
|
||||
set:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
<code class="methodname">JoinConfig.setNoSort()</code>
|
||||
</p>
|
||||
<p>
|
||||
Specifies whether automatic sorting of input cursors is disabled. The cursors are sorted from the
|
||||
one that refers to the least number of data items to the one that refers to the most.
|
||||
</p>
|
||||
<p>
|
||||
If the data is structured so that cursors with many data items also share many common elements,
|
||||
higher performance will result from listing those cursors before cursors with fewer data
|
||||
items. Turning off sorting permits applications to specify cursors in the proper order given this
|
||||
scenario.
|
||||
</p>
|
||||
<p>
|
||||
The default value is <code class="literal">false</code> (automatic cursor sorting is performed).
|
||||
</p>
|
||||
<p>
|
||||
For example:
|
||||
</p>
|
||||
<a id="je_index10"></a>
|
||||
<pre class="programlisting">// All database and environments omitted
|
||||
JoinConfig config = new JoinConfig();
|
||||
config.setNoSort(true);
|
||||
JoinCursor joinCursor = myDb.join(cursorArray, config); </pre>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="secondaryCursor.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="indexes.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="indexusage.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">
|
||||
<span>Using Secondary Cursors</span>
|
||||
|
||||
</td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Secondary Database Example</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
241
docs/GettingStartedGuide/keyCreator.html
Normal file
241
docs/GettingStartedGuide/keyCreator.html
Normal file
|
|
@ -0,0 +1,241 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Implementing Key Creators</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="indexes.html" title="Chapter 10. Secondary Databases" />
|
||||
<link rel="prev" href="indexes.html" title="Chapter 10. Secondary Databases" />
|
||||
<link rel="next" href="secondaryProps.html" title="Secondary Database Properties" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Implementing Key
|
||||
<span xmlns="http://www.w3.org/1999/xhtml">Creators</span>
|
||||
|
||||
</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="indexes.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 10. Secondary Databases</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="secondaryProps.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="keyCreator"></a>Implementing Key
|
||||
<span>Creators</span>
|
||||
|
||||
</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
You must provide every secondary database with a
|
||||
<span>class</span>
|
||||
|
||||
that creates keys from primary records. You identify this
|
||||
<span>class</span>
|
||||
|
||||
|
||||
<span>
|
||||
using the <code class="methodname">SecondaryConfig.setKeyCreator()</code>
|
||||
method.
|
||||
</span>
|
||||
|
||||
</p>
|
||||
<p>
|
||||
You can create keys using whatever data you want. Typically you will
|
||||
base your key on some information found in a record's data, but you
|
||||
can also use information found in the primary record's key. How you build
|
||||
your keys is entirely dependent upon the nature of the index that you
|
||||
want to maintain.
|
||||
</p>
|
||||
<p>
|
||||
You implement a key creator by writing a class that implements the
|
||||
<code class="classname">SecondaryKeyCreator</code> interface. This interface
|
||||
requires you to implement the <code class="methodname">SecondaryKeyCreator.createSecondaryKey()</code>
|
||||
method.
|
||||
</p>
|
||||
<p>
|
||||
One thing to remember when implementing this method is that you will
|
||||
need a way to extract the necessary information from the data's
|
||||
<code class="classname">DatabaseEntry</code> and/or the key's
|
||||
<code class="classname">DatabaseEntry</code> that are provided on calls to this
|
||||
method. If you are using complex objects, then you are probably using the
|
||||
Bind APIs to perform this conversion. The easiest thing to do is to
|
||||
instantiate the <code class="classname">EntryBinding</code> or
|
||||
<code class="classname">TupleBinding</code> that you need to perform the
|
||||
conversion, and then provide this to your key creator's constructor.
|
||||
The Bind APIs are introduced in <a class="xref" href="bindAPI.html" title="Using the BIND APIs">Using the BIND APIs</a>.
|
||||
</p>
|
||||
<p>
|
||||
<code class="methodname">SecondaryKeyCreator.createSecondaryKey()</code> returns a
|
||||
boolean. A return value of <code class="literal">false</code> indicates that
|
||||
no secondary key exists, and therefore no record should be added to the secondary database for that primary record.
|
||||
If a record already exists in the secondary database, it is deleted.
|
||||
</p>
|
||||
<p>
|
||||
For example, suppose your primary database uses the following class
|
||||
for its record data:
|
||||
</p>
|
||||
<a id="je_index3"></a>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
public class PersonData {
|
||||
private String userID;
|
||||
private String surname;
|
||||
private String familiarName;
|
||||
|
||||
public PersonData(String userID, String surname,
|
||||
String familiarName) {
|
||||
this.userID = userID;
|
||||
this.surname = surname;
|
||||
this.familiarName = familiarName;
|
||||
}
|
||||
|
||||
public String getUserID() {
|
||||
return userID;
|
||||
}
|
||||
|
||||
public String getSurname() {
|
||||
return surname;
|
||||
}
|
||||
|
||||
public String getFamiliarName() {
|
||||
return familiarName;
|
||||
}
|
||||
} </pre>
|
||||
<p>
|
||||
Also, suppose that you have created a custom tuple binding,
|
||||
<code class="classname">PersonDataBinding</code>, that you use to convert
|
||||
<code class="classname">PersonData</code> objects to and from
|
||||
<code class="classname">DatabaseEntry</code> objects. (Custom tuple bindings are
|
||||
described in <a class="xref" href="bindAPI.html#customTuple" title="Custom Tuple Bindings">Custom Tuple Bindings</a>.)
|
||||
</p>
|
||||
<p>
|
||||
Finally, suppose you want a secondary database that is keyed based
|
||||
on the person's full name.
|
||||
</p>
|
||||
<p>
|
||||
Then in this case you might create a key creator as follows:
|
||||
</p>
|
||||
<a id="je_index4"></a>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.bind.tuple.TupleBinding;
|
||||
|
||||
import com.sleepycat.je.SecondaryKeyCreator;
|
||||
import com.sleepycat.je.DatabaseEntry;
|
||||
import com.sleepycat.je.DatabaseException;
|
||||
import com.sleepycat.je.SecondaryDatabase;
|
||||
|
||||
import java.io.IOException;
|
||||
|
||||
public class FullNameKeyCreator implements SecondaryKeyCreator {
|
||||
|
||||
private TupleBinding theBinding;
|
||||
|
||||
public FullNameKeyCreator(TupleBinding theBinding1) {
|
||||
theBinding = theBinding1;
|
||||
}
|
||||
|
||||
public boolean createSecondaryKey(SecondaryDatabase secDb,
|
||||
DatabaseEntry keyEntry,
|
||||
DatabaseEntry dataEntry,
|
||||
DatabaseEntry resultEntry) {
|
||||
|
||||
try {
|
||||
PersonData pd =
|
||||
(PersonData) theBinding.entryToObject(dataEntry);
|
||||
String fullName = pd.getFamiliarName() + " " +
|
||||
pd.getSurname();
|
||||
resultEntry.setData(fullName.getBytes("UTF-8"));
|
||||
} catch (IOException willNeverOccur) {}
|
||||
return true;
|
||||
}
|
||||
} </pre>
|
||||
<p>Finally, you use this key creator as follows:</p>
|
||||
<a id="je_index5"></a>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.bind.tuple.TupleBinding;
|
||||
|
||||
import com.sleepycat.je.Database;
|
||||
import com.sleepycat.je.DatabaseException;
|
||||
import com.sleepycat.je.Environment;
|
||||
import com.sleepycat.je.SecondaryDatabase;
|
||||
import com.sleepycat.je.SecondaryConfig;
|
||||
|
||||
...
|
||||
|
||||
Environment myEnv = null;
|
||||
Database myDb = null;
|
||||
SecondaryDatabase mySecDb = null;
|
||||
try {
|
||||
// Environment and primary database open omitted for brevity
|
||||
...
|
||||
|
||||
TupleBinding myDataBinding = new MyTupleBinding();
|
||||
FullNameKeyCreator fnkc = new FullNameKeyCreator(myDataBinding);
|
||||
|
||||
SecondaryConfig mySecConfig = new SecondaryConfig();
|
||||
mySecConfig.setKeyCreator(fnkc);
|
||||
|
||||
//Perform the actual open
|
||||
String secDbName = "mySecondaryDatabase";
|
||||
mySecDb = myEnv.openSecondaryDatabase(null, secDbName, myDb,
|
||||
mySecConfig);
|
||||
} catch (DatabaseException de) {
|
||||
// Exception handling goes here
|
||||
} finally {
|
||||
try {
|
||||
if (mySecDb != null) {
|
||||
mySecDb.close();
|
||||
}
|
||||
|
||||
if (myDb != null) {
|
||||
myDb.close();
|
||||
}
|
||||
|
||||
if (myEnv != null) {
|
||||
myEnv.close();
|
||||
}
|
||||
} catch (DatabaseException dbe) {
|
||||
// Exception handling goes here
|
||||
}
|
||||
}</pre>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="indexes.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="indexes.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="secondaryProps.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Chapter 10. Secondary Databases </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Secondary Database Properties</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
133
docs/GettingStartedGuide/logfilesrevealed.html
Normal file
133
docs/GettingStartedGuide/logfilesrevealed.html
Normal file
|
|
@ -0,0 +1,133 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Six Things Everyone Should Know about JE Log Files</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="introduction.html" title="Chapter 1. Introduction to Berkeley DB Java Edition" />
|
||||
<link rel="prev" href="jeexceptions.html" title="JE Exceptions" />
|
||||
<link rel="next" href="env.html" title="Chapter 2. Database Environments" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Six Things Everyone Should Know about JE Log Files</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="jeexceptions.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 1. Introduction to Berkeley DB Java Edition </th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="env.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="logfilesrevealed"></a>Six Things Everyone Should Know about JE Log Files</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
JE log files are not like the log files of other database systems. Nor are they like the log files or database
|
||||
files created by Berkeley DB C Edition. In this guide you will learn more about log files as you go along, but it is good
|
||||
to keep the following points in mind as you begin using JE.
|
||||
</p>
|
||||
<div class="orderedlist">
|
||||
<ol type="1">
|
||||
<li>
|
||||
<p>
|
||||
JE log files are "append only". Record insertions, deletions, and updates are always added at the end
|
||||
of the current file. The first file is named <code class="literal">00000000.jdb</code>. When that file grows to a certain size
|
||||
(10 MB by default) a new file named <code class="literal">00000001.jdb</code> becomes the current file, and so on.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
There are no separate database files. Unlike Berkeley DB C Edition, databases are not stored in files
|
||||
that are separate from the transaction log. The transaction log and the database records are stored
|
||||
together in a single sequential log consisting of multiple log files.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
The JE cleaner is responsible for reclaiming unused disk space. When the records in a log file are
|
||||
superseded by deletions or updates recorded in a later log file, the older log file is no longer fully
|
||||
utilized. The cleaner, which operates by default as a separate thread, determines the least utilized
|
||||
log files, copies any still utilized records in those files to the end of the current log file, and
|
||||
finally deletes the now completely un-utilized log file.
|
||||
</p>
|
||||
<p>
|
||||
See <a class="xref" href="backgroundthreads.html#cleaner" title="The Cleaner Thread">The Cleaner Thread</a> for more information on the cleaner.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Cleaning does not start immediately and never produces 100% utilization. Until you have written enough
|
||||
data to create several log files, and some of that data is obsoleted through deletions and updates, you
|
||||
will not notice any log files being deleted by the cleaner. By default cleaning occurs in the background and
|
||||
maintains the log files at 50% utilization. You can configure a higher utilization value, but
|
||||
configuring too high a utilization value will reduce overall performance.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Cleaning is not automatically performed when closing the environment. If you wish to reduce unused disk
|
||||
space to a minimum at a particular point in time, you must explicitly call a method to perform log
|
||||
cleaning. See the <a class="xref" href="envclose.html" title="Closing Database Environments">Closing Database Environments</a> for more information.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Log file deletion only occurs after a checkpoint. The cleaner prepares log files to be deleted, but
|
||||
file deletion must be performed after a checkpoint to ensure that the files are no longer referenced.
|
||||
Checkpoints occur on their own schedule, which is every 20 MB of log written, by default. This is part
|
||||
of the reason that you will not see log files being deleted until after several files have been created.
|
||||
</p>
|
||||
<p>
|
||||
When using JE's replication (high availability) feature, a checkpoint does not delete
|
||||
the cleaned log file but instead instead changes the status of the file to <span class="emphasis"><em>reserved</em></span>.
|
||||
Reserved files are only deleted when disk utilization exceeds the values set for either
|
||||
<a class="ulink" href="../java/com/sleepycat/je/EnvironmentConfig.html#MAX_DISK" target="_top">EnvironmentConfig.MAX_DISK</a> or <a class="ulink" href="../java/com/sleepycat/je/EnvironmentConfig.html#FREE_DISK" target="_top">EnvironmentConfig.FREE_DISK</a>.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Log files can be spread across multiple directories, and therefore across multiple
|
||||
disks through the use of links or mount points. See
|
||||
<a class="xref" href="env.html#multisubdir" title="Multiple Environment Subdirectories">Multiple Environment Subdirectories</a>
|
||||
for more information.
|
||||
</p>
|
||||
</li>
|
||||
</ol>
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="jeexceptions.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="introduction.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="env.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">JE Exceptions </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Chapter 2. Database Environments</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
260
docs/GettingStartedGuide/managelogging.html
Normal file
260
docs/GettingStartedGuide/managelogging.html
Normal file
|
|
@ -0,0 +1,260 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Logging</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="administration.html" title="Chapter 12. Administering Berkeley DB Java Edition Applications" />
|
||||
<link rel="prev" href="commandlinetools.html" title="The Command Line Tools" />
|
||||
<link rel="next" href="concurrentProcessing.html" title="Appendix A. Concurrent Processing in Berkeley DB Java Edition" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Logging</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="commandlinetools.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 12. Administering Berkeley DB Java Edition Applications</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="concurrentProcessing.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="managelogging"></a>Logging</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="toc">
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="managelogging.html#logginglevels">Managing Logging Levels</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="managelogging.html#handlerlevels">Managing Handler Levels</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</div>
|
||||
<p>
|
||||
JE uses the <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/logging/package-summary.html" target="_top">java.util.logging</a> package to
|
||||
log operations and trace messages. A distinct logger is defined for
|
||||
each significant component of the system. The use of distinct loggers, along with
|
||||
controllable logging levels, allows the logging output to be
|
||||
tuned to tell you exactly what you need to know (while avoiding a lot of
|
||||
extra information that only gets in the way) in order to monitor
|
||||
your application's activities and/or debug runtime problems.
|
||||
</p>
|
||||
<p>
|
||||
Logging output can be displayed to the console and the
|
||||
<code class="filename">je.info</code> file in your application's
|
||||
environment directory. Setting the logger level controls the
|
||||
types of messages that are published to the handlers. Setting the handler level
|
||||
determines if and where the published messages are displayed.
|
||||
</p>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="logginglevels"></a>Managing Logging Levels</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
The default logging level for JE loggers is
|
||||
<code class="literal">INFO</code>. At that level, a non-replicated
|
||||
environment issues messages only when critical exceptions are
|
||||
encountered. A replicated environment issues node transition
|
||||
messages which should be comprehensible to the user familiar with
|
||||
the replication group life cycle and can be extremely useful when
|
||||
monitoring your application's activities. The output at the
|
||||
<code class="literal">INFO</code> is not verbose; it simply details the
|
||||
node start up and shutdown operations. Initial configuration
|
||||
problems, if any, should show up during the startup operation.
|
||||
You are strongly advised to run your production application with
|
||||
this level of logging.
|
||||
</p>
|
||||
<p>
|
||||
Finer levels of logging are available for debugging purposes.
|
||||
These will generate verbose output that is rich in implementation
|
||||
detail. The output at these levels is only likely to be helpful
|
||||
to people familiar with JE's implementation and the
|
||||
application's use of JE, so you should only configure your logging
|
||||
for these more verbose levels if you are involved in a detailed
|
||||
debugging effort.
|
||||
</p>
|
||||
<p>
|
||||
To set or change the logger level <span class="emphasis"><em>before</em></span> the environment is
|
||||
opened, do one of the following:
|
||||
</p>
|
||||
<div class="orderedlist">
|
||||
<ol type="1">
|
||||
<li>
|
||||
<p>
|
||||
Set logging levels using the standard Java <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/logging/LogManager.html" target="_top">LogManager</a>
|
||||
properties file. For example, you can set:
|
||||
</p>
|
||||
<pre class="programlisting">com.sleepycat.je.level=INFO</pre>
|
||||
<p>
|
||||
in the <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/logging/LogManager.html" target="_top">LogManager</a> properties file to set the logger
|
||||
level for all JE loggers.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Set logging levels programmatically using the
|
||||
<a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/logging/package-summary.html" target="_top">java.util.logging</a> API. For example:
|
||||
</p>
|
||||
<pre class="programlisting">...
|
||||
// All other imports are omitted for brevity
|
||||
import java.util.logging.Logger;
|
||||
...
|
||||
|
||||
Logger parent = Logger.getLogger("com.sleepycat.je");
|
||||
parent.setLevel(Level.FINE); // Loggers will now publish more
|
||||
// detailed messages. </pre>
|
||||
</li>
|
||||
</ol>
|
||||
</div>
|
||||
<p>
|
||||
To set or change the logger level <span class="emphasis"><em>after</em></span> the environment is
|
||||
opened, do one of the following:
|
||||
</p>
|
||||
<div class="orderedlist">
|
||||
<ol type="1">
|
||||
<li>
|
||||
<p>
|
||||
Use the standard java.util.logging MBean to set a
|
||||
concrete JE logger.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Use the JEDiagnostic MBean to set the parent
|
||||
<code class="literal">com.sleepycat.je</code> logger.
|
||||
See the <a class="ulink" href="..//jconsole/JConsole-plugin.html" target="_top">JConsole Plugin</a> page for information on
|
||||
this MBean.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Use the programmatic <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/logging/package-summary.html" target="_top">java.util.logging</a> API described
|
||||
above to change the logger.
|
||||
</p>
|
||||
</li>
|
||||
</ol>
|
||||
</div>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="handlerlevels"></a>Managing Handler Levels</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
Output to the <code class="filename">je.info</code> file is managed by
|
||||
the JE <a class="ulink" href="../java/com/sleepycat/je/util/FileHandler.html" target="_top">FileHandler</a>, while output to the console is managed
|
||||
by the JE <a class="ulink" href="../java/com/sleepycat/je/util/ConsoleHandler.html" target="_top">ConsoleHandler</a>. By default, no output is shown on
|
||||
the console, and only <code class="literal">INFO</code> level messages are
|
||||
sent to <code class="filename">je.info</code>.
|
||||
</p>
|
||||
<p>
|
||||
To set or change the handler level <span class="emphasis"><em>before</em></span> the environment is
|
||||
opened, do one of the following:
|
||||
</p>
|
||||
<div class="orderedlist">
|
||||
<ol type="1">
|
||||
<li>
|
||||
<p>
|
||||
Set logging levels using the standard Java
|
||||
<a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/logging/LogManager.html" target="_top">LogManager</a> properties file. For example, you can
|
||||
set:
|
||||
</p>
|
||||
<pre class="programlisting">com.sleepycat.je.util.FileHandler.level=ALL
|
||||
com.sleepycat.je.util.ConsoleHandler.level=ALL</pre>
|
||||
<p>
|
||||
in the <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/logging/LogManager.html" target="_top">LogManager</a> properties file to display all
|
||||
logging output to the console and
|
||||
<code class="filename">je.info</code> files.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
The <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/logging/package-summary.html" target="_top">java.util.logging</a> package does not supply an
|
||||
API for setting handler levels. Instead, use the
|
||||
following JE environment parameter:
|
||||
</p>
|
||||
<pre class="programlisting">...
|
||||
EnvironmentConfig envConfig = new EnvironmentConfig();
|
||||
envConfig.setAllowCreate(true);
|
||||
envConfig.setConfigParam(EnvironmentConfig.FILE_LOGGING_LEVEL, "ALL");
|
||||
envConfig.setConfigParam(EnvironmentConfig.CONSOLE_LOGGING_LEVEL,
|
||||
"ALL");
|
||||
|
||||
...
|
||||
// Open your environment as normal here
|
||||
... </pre>
|
||||
</li>
|
||||
</ol>
|
||||
</div>
|
||||
<p>
|
||||
To set or change the handler level <span class="emphasis"><em>after</em></span> the environment is
|
||||
opened, do one of the following:
|
||||
</p>
|
||||
<div class="orderedlist">
|
||||
<ol type="1">
|
||||
<li>
|
||||
<p>
|
||||
Use <a class="ulink" href="../java/com/sleepycat/je/EnvironmentMutableConfig.html#setConfigParam(java.lang.String, java.lang.String)" target="_top">EnvironmentMutableConfig.setConfigParam()</a> to change the
|
||||
handler levels using the JE properties described
|
||||
above.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Use the JEDiagnostic MBean to change handler levels.
|
||||
See the <a class="ulink" href="..//jconsole/JConsole-plugin.html" target="_top">JConsole Plugin</a> page for information on
|
||||
this MBean.
|
||||
</p>
|
||||
</li>
|
||||
</ol>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="commandlinetools.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="administration.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="concurrentProcessing.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">The Command Line Tools </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Appendix A. Concurrent Processing in Berkeley DB Java Edition</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
165
docs/GettingStartedGuide/moreinfo.html
Normal file
165
docs/GettingStartedGuide/moreinfo.html
Normal file
|
|
@ -0,0 +1,165 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>For More Information</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="preface.html" title="Preface" />
|
||||
<link rel="prev" href="preface.html" title="Preface" />
|
||||
<link rel="next" href="introduction.html" title="Chapter 1. Introduction to Berkeley DB Java Edition" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">For More Information</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="preface.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Preface</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="introduction.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="moreinfo"></a>For More Information</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="toc">
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="moreinfo.html#contact_us">Contact Us</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</div>
|
||||
<p>
|
||||
Beyond this manual, you may also find the following sources of
|
||||
information useful when building a JE application:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
<a class="ulink" href="http://docs.oracle.com/cd/E17277_02/html/TransactionGettingStarted/index.html" target="_top">
|
||||
Berkeley DB, Java Edition Getting Started with Transaction Processing
|
||||
</a>
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<a class="ulink" href="http://docs.oracle.com/cd/E17277_02/html/ReplicationGuide/index.html" target="_top">
|
||||
Berkeley DB, Java Edition Getting Started with High Availability Applications
|
||||
</a>
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<span>
|
||||
|
||||
|
||||
</span>
|
||||
|
||||
|
||||
|
||||
|
||||
<a class="ulink" href="http://docs.oracle.com/cd/E17277_02/html/java/index.html" target="_top">
|
||||
Berkeley DB, Java Edition Javadoc
|
||||
</a>
|
||||
|
||||
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<a class="ulink" href="http://docs.oracle.com/cd/E17277_02/html/collections/tutorial/index.html" target="_top">
|
||||
Berkeley DB, Java Edition Collections Tutorial
|
||||
</a>
|
||||
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<span>
|
||||
<p>
|
||||
To download the latest
|
||||
|
||||
<span>Berkeley DB Java Edition</span>
|
||||
|
||||
documentation along with white papers and other collateral,
|
||||
visit <a class="ulink" href="http://www.oracle.com/technetwork/indexes/documentation/index.html" target="_top">http://www.oracle.com/technetwork/indexes/documentation/index.html</a>.
|
||||
</p>
|
||||
<p>
|
||||
For the latest version of the Oracle
|
||||
|
||||
<span>Berkeley DB Java Edition</span>
|
||||
|
||||
downloads, visit
|
||||
<a class="ulink" href="http://www.oracle.com/technetwork/database/database-technologies/berkeleydb/downloads/index.html" target="_top">http://www.oracle.com/technetwork/database/database-technologies/berkeleydb/downloads/index.html</a>.
|
||||
</p>
|
||||
</span>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="contact_us"></a>Contact Us</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
You can post your comments and questions at the Oracle
|
||||
Technology (OTN) forum for
|
||||
|
||||
|
||||
<span>
|
||||
Oracle Berkeley DB Java Edition at: <a class="ulink" href="https://forums.oracle.com/forums/forum.jspa?forumID=273" target="_top">https://forums.oracle.com/forums/forum.jspa?forumID=273</a>.
|
||||
</span>
|
||||
</p>
|
||||
<p>
|
||||
For sales or support information, email to:
|
||||
<a class="ulink" href="mailto:berkeleydb-info_us@oracle.com" target="_top">berkeleydb-info_us@oracle.com</a>
|
||||
You can subscribe to a low-volume email announcement list for
|
||||
the Berkeley DB product family by sending email to:
|
||||
<a class="ulink" href="mailto:bdb-join@oss.oracle.com" target="_top">bdb-join@oss.oracle.com</a>
|
||||
</p>
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="preface.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="preface.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="introduction.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Preface </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Chapter 1. Introduction to Berkeley DB Java Edition </td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
89
docs/GettingStartedGuide/multiprocess.html
Normal file
89
docs/GettingStartedGuide/multiprocess.html
Normal file
|
|
@ -0,0 +1,89 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Multiprocess Applications</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="concurrentProcessing.html" title="Appendix A. Concurrent Processing in Berkeley DB Java Edition" />
|
||||
<link rel="prev" href="concurrentProcessing.html" title="Appendix A. Concurrent Processing in Berkeley DB Java Edition" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Multiprocess Applications</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="concurrentProcessing.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Appendix A. Concurrent Processing in Berkeley DB Java Edition</th>
|
||||
<td width="20%" align="right"> </td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="multiprocess"></a>Multiprocess Applications</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
Note the following if you are writing an application that wants to access JE databases from multiple
|
||||
processes:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
In JE, you must use environments. Further, a database can be opened for write access only if the
|
||||
environment is opened for write access. Finally, only one process may have an environment opened for
|
||||
write access at a time.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
If your process attempts to open an environment for write, and another process has already opened that
|
||||
environment for write, then the open will fail. In this event, the process must either exit or open the
|
||||
environment as read-only.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
A process that opens an environment for read-only receives a snapshot of the data in that environment.
|
||||
If another process modifies the environment's databases in any way, the read-only version of the data
|
||||
will not be updated until the read-only process closes and reopens the environment (and by extension all
|
||||
databases in that environment).
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="concurrentProcessing.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="concurrentProcessing.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> </td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Appendix A. Concurrent Processing in Berkeley DB Java Edition </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> </td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
156
docs/GettingStartedGuide/mydbenv-persist.html
Normal file
156
docs/GettingStartedGuide/mydbenv-persist.html
Normal file
|
|
@ -0,0 +1,156 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>MyDbEnv</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="dpl_example.html" title="Chapter 6. A DPL Example" />
|
||||
<link rel="prev" href="inventoryclass.html" title="Inventory.java" />
|
||||
<link rel="next" href="dataaccessorclass.html" title="DataAccessor.java" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">MyDbEnv</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="inventoryclass.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 6. A DPL Example</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="dataaccessorclass.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="mydbenv-persist"></a>MyDbEnv</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
The applications that we are building for our example both
|
||||
must open and close environments and entity stores. One
|
||||
of our applications is writing to the entity store, so this
|
||||
application needs to open the store as read-write. It also
|
||||
wants to be able to create the store if it does not exist.
|
||||
</p>
|
||||
<p>
|
||||
Our second application only reads from the store. In this
|
||||
case, the store should be opened as read-only.
|
||||
</p>
|
||||
<p>
|
||||
We perform these activities by creating a single class that
|
||||
is responsible for opening and closing our store and
|
||||
environment. This class is shared by both our applications.
|
||||
To use it, callers need to only provide the path to the
|
||||
environment home directory, and to indicate whether the
|
||||
object is meant to be read-only. The class implementation
|
||||
is as follows:
|
||||
</p>
|
||||
<pre class="programlisting">package persist.gettingStarted;
|
||||
|
||||
import java.io.File;
|
||||
|
||||
import com.sleepycat.je.DatabaseException;
|
||||
import com.sleepycat.je.Environment;
|
||||
import com.sleepycat.je.EnvironmentConfig;
|
||||
|
||||
import com.sleepycat.persist.EntityStore;
|
||||
import com.sleepycat.persist.StoreConfig;
|
||||
|
||||
public class MyDbEnv {
|
||||
|
||||
private Environment myEnv;
|
||||
private EntityStore store;
|
||||
|
||||
// Our constructor does nothing
|
||||
public MyDbEnv() {}
|
||||
|
||||
// The setup() method opens the environment and store
|
||||
// for us.
|
||||
public void setup(File envHome, boolean readOnly)
|
||||
throws DatabaseException {
|
||||
|
||||
EnvironmentConfig myEnvConfig = new EnvironmentConfig();
|
||||
StoreConfig storeConfig = new StoreConfig();
|
||||
|
||||
myEnvConfig.setReadOnly(readOnly);
|
||||
storeConfig.setReadOnly(readOnly);
|
||||
|
||||
// If the environment is opened for write, then we want to be
|
||||
// able to create the environment and entity store if
|
||||
// they do not exist.
|
||||
myEnvConfig.setAllowCreate(!readOnly);
|
||||
storeConfig.setAllowCreate(!readOnly);
|
||||
|
||||
// Open the environment and entity store
|
||||
myEnv = new Environment(envHome, myEnvConfig);
|
||||
store = new EntityStore(myEnv, "EntityStore", storeConfig);
|
||||
|
||||
}
|
||||
|
||||
// Return a handle to the entity store
|
||||
public EntityStore getEntityStore() {
|
||||
return store;
|
||||
}
|
||||
|
||||
// Return a handle to the environment
|
||||
public Environment getEnv() {
|
||||
return myEnv;
|
||||
}
|
||||
|
||||
// Close the store and environment.
|
||||
public void close() {
|
||||
if (store != null) {
|
||||
try {
|
||||
store.close();
|
||||
} catch(DatabaseException dbe) {
|
||||
System.err.println("Error closing store: " +
|
||||
dbe.toString());
|
||||
System.exit(-1);
|
||||
}
|
||||
}
|
||||
|
||||
if (myEnv != null) {
|
||||
try {
|
||||
// Finally, close the environment.
|
||||
myEnv.close();
|
||||
} catch(DatabaseException dbe) {
|
||||
System.err.println("Error closing MyDbEnv: " +
|
||||
dbe.toString());
|
||||
System.exit(-1);
|
||||
}
|
||||
}
|
||||
}
|
||||
} </pre>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="inventoryclass.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="dpl_example.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="dataaccessorclass.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Inventory.java </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> DataAccessor.java</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
243
docs/GettingStartedGuide/persist_access.html
Normal file
243
docs/GettingStartedGuide/persist_access.html
Normal file
|
|
@ -0,0 +1,243 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Chapter 5. Saving and Retrieving Objects</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="dpl.html" title="Part I. Programming with the Direct Persistence Layer" />
|
||||
<link rel="prev" href="dplindexcreate.html" title="Creating Indexes" />
|
||||
<link rel="next" href="simpleda.html" title="SimpleDA.class" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Chapter 5. Saving and Retrieving Objects</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="dplindexcreate.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Part I. Programming with the Direct Persistence Layer</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="simpleda.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="chapter" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title"><a id="persist_access"></a>Chapter 5. Saving and Retrieving Objects</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="toc">
|
||||
<p>
|
||||
<b>Table of Contents</b>
|
||||
</p>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="persist_access.html#simpleentity">A Simple Entity Class</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="simpleda.html">SimpleDA.class</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="simpleput.html">Placing Objects in an Entity Store</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="simpleget.html">Retrieving Objects from an Entity Store</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="getmultiple.html">Retrieving Multiple Objects</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="getmultiple.html#dpl_cursor_initialize">Cursor Initialization</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="getmultiple.html#dpl_dups">Working with Duplicate Keys</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="getmultiple.html#dpl_cursor_range">Key Ranges</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="dpl_entityjoin.html">Join Cursors</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="dpl_delete.html">Deleting Entity Objects</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="dpl_replace.html">Replacing Entity Objects</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</div>
|
||||
<p>
|
||||
To store an object in an <code class="classname">EntityStore</code> you
|
||||
must annotate the class appropriately and then store it using
|
||||
<code class="methodname">PrimaryIndex.put()</code>.
|
||||
</p>
|
||||
<p>
|
||||
To retrieve and object from an <code class="classname">EntityStore</code>
|
||||
you use the <code class="methodname">get()</code> method from either the
|
||||
<code class="classname">PrimaryIndex</code> or
|
||||
<code class="classname">SecondaryIndex</code>, whichever is most
|
||||
appropriate for your application.
|
||||
</p>
|
||||
<p>
|
||||
In both cases, it simplifies things greatly if you create a data
|
||||
accessor class to organize your indexes.
|
||||
</p>
|
||||
<p>
|
||||
In the next few sections we:
|
||||
</p>
|
||||
<div class="orderedlist">
|
||||
<ol type="1">
|
||||
<li>
|
||||
<p>
|
||||
Create an entity class that is ready to be stored
|
||||
in an entity store. This class will have both a
|
||||
primary index (required) declared for it, as well
|
||||
as a secondary index (which is optional).
|
||||
</p>
|
||||
<p>
|
||||
See the next section for this implementation.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Create a data accessor class which is used to
|
||||
organize our data.
|
||||
</p>
|
||||
<p>
|
||||
See <a class="xref" href="simpleda.html" title="SimpleDA.class">SimpleDA.class</a>
|
||||
for this implementation.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Create a simple class that is used to put objects
|
||||
to our entity store.
|
||||
</p>
|
||||
<p>
|
||||
See <a class="xref" href="simpleput.html" title="Placing Objects in an Entity Store">Placing Objects in an Entity Store</a>
|
||||
for this implementation.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Create another class that retrieves objects from
|
||||
our entity store.
|
||||
</p>
|
||||
<p>
|
||||
See <a class="xref" href="simpleget.html" title="Retrieving Objects from an Entity Store">Retrieving Objects from an Entity Store</a>
|
||||
for this implementation.
|
||||
</p>
|
||||
</li>
|
||||
</ol>
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="simpleentity"></a>A Simple Entity Class</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
For clarity's sake, this entity class is as simple a class as we can write.
|
||||
It contains only two data members, both of which are set
|
||||
and retrieved by simple setter and getter methods. Beyond
|
||||
that, by design this class does not do anything of particular
|
||||
interest.
|
||||
</p>
|
||||
<p>
|
||||
Its implementation is as follows:
|
||||
</p>
|
||||
<pre class="programlisting">package persist.gettingStarted;
|
||||
|
||||
import com.sleepycat.persist.model.Entity;
|
||||
import com.sleepycat.persist.model.PrimaryKey;
|
||||
import static com.sleepycat.persist.model.Relationship.*;
|
||||
import com.sleepycat.persist.model.SecondaryKey;
|
||||
|
||||
@Entity
|
||||
public class SimpleEntityClass {
|
||||
|
||||
// Primary key is pKey
|
||||
@PrimaryKey
|
||||
private String pKey;
|
||||
|
||||
// Secondary key is the sKey
|
||||
@SecondaryKey(relate=MANY_TO_ONE)
|
||||
private String sKey;
|
||||
|
||||
public void setPKey(String data) {
|
||||
pKey = data;
|
||||
}
|
||||
|
||||
public void setSKey(String data) {
|
||||
sKey = data;
|
||||
}
|
||||
|
||||
public String getPKey() {
|
||||
return pKey;
|
||||
}
|
||||
|
||||
public String getSKey() {
|
||||
return sKey;
|
||||
}
|
||||
} </pre>
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="dplindexcreate.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="dpl.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="simpleda.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Creating Indexes </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> SimpleDA.class</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
316
docs/GettingStartedGuide/persist_first.html
Normal file
316
docs/GettingStartedGuide/persist_first.html
Normal file
|
|
@ -0,0 +1,316 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Chapter 3. Direct Persistence Layer First Steps</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="dpl.html" title="Part I. Programming with the Direct Persistence Layer" />
|
||||
<link rel="prev" href="dpl.html" title="Part I. Programming with the Direct Persistence Layer" />
|
||||
<link rel="next" href="persistobject.html" title="Persistent Objects" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Chapter 3. Direct Persistence Layer First Steps</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="dpl.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Part I. Programming with the Direct Persistence Layer</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="persistobject.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="chapter" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title"><a id="persist_first"></a>Chapter 3. Direct Persistence Layer First Steps</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="toc">
|
||||
<p>
|
||||
<b>Table of Contents</b>
|
||||
</p>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="persist_first.html#entitystore">Entity Stores</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="persist_first.html#persist-open">Opening and Closing Environments and Stores</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="persistobject.html">Persistent Objects</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="saveret.html">Saving and Retrieving Data</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</div>
|
||||
<p>
|
||||
This chapter guides you through the first few steps required to
|
||||
use the DPL with your application. These steps include:
|
||||
</p>
|
||||
<div class="orderedlist">
|
||||
<ol type="1">
|
||||
<li>
|
||||
<p>
|
||||
Opening your environment as was described in
|
||||
<span>
|
||||
<a class="xref" href="env.html#envopen" title="Opening Database Environments">Opening Database Environments</a>.
|
||||
</span>
|
||||
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Opening your entity store.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Identifying the classes that you want to store in
|
||||
JE as either a <code class="literal">persistent</code>
|
||||
class or an <code class="literal">entity</code>.
|
||||
</p>
|
||||
</li>
|
||||
</ol>
|
||||
</div>
|
||||
<p>
|
||||
Once you have done these things, you can write your classes to
|
||||
the JE databases, read them back from the databases, delete
|
||||
them from the databases, and so forth. These activities are
|
||||
described in the chapters that follow in this part of this manual.
|
||||
</p>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="entitystore"></a>Entity Stores</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="toc">
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="persist_first.html#persist-open">Opening and Closing Environments and Stores</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</div>
|
||||
<p>
|
||||
Entity stores are the basic unit of storage that you use with the DPL. That is, it
|
||||
is a unit of encapsulation for the classes that you want to store in JE. Under
|
||||
the hood it actually interacts with JE databases, but the DPL provides a layer
|
||||
of abstraction from the underlying JE APIs. The store, therefore, provides a
|
||||
simplified mechanism by which you read and write your stored classes. By using a
|
||||
store, you have access to your classes that is more simplified than if you were
|
||||
interacting with databases directly, but this simplified access comes at the cost of
|
||||
reduced flexibility.
|
||||
</p>
|
||||
<p>
|
||||
Entity stores have configurations in the same way that environments have
|
||||
configurations. You can use a <code class="classname">StoreConfig</code> object
|
||||
to identify store properties. Among these are methods that allow you to declare
|
||||
whether:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
the store can be created if it does not exist at the time
|
||||
it is opened. Use the
|
||||
<code class="methodname">StoreConfig.setAllowCreate()</code>
|
||||
method to set this.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
deferred writes are allowed for the store. Use the
|
||||
<code class="methodname">StoreConfig.setDeferredWrite()</code>
|
||||
method to set this. See
|
||||
<a class="xref" href="databases.html#dwdatabase" title="Deferred Write Databases">Deferred Write Databases</a>
|
||||
for general information on deferred write
|
||||
databases.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
the store is read-only. Use the
|
||||
<code class="methodname">StoreConfig.setReadOnly()</code>
|
||||
method to set this.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
the store supports transactions. Use the
|
||||
<code class="methodname">StoreConfig.setTransactional()</code>
|
||||
method to set this.
|
||||
</p>
|
||||
<p>
|
||||
Writing JE transactional applications is described in the
|
||||
<em class="citetitle">Berkeley DB, Java Edition Getting Started with Transaction Processing</em> guide.
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<p>
|
||||
<code class="classname">EntityStore</code> objects also provide methods for retrieving
|
||||
information about the store, such as:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
the store's name. Use the
|
||||
<code class="methodname">EntityStore.getStoreName()</code>
|
||||
method to retrieve this.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
a handle to the environment in which the store is opened. Use the
|
||||
<code class="methodname">EntityStore.getEnvironment</code>
|
||||
method to retrieve this handle.
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<p>
|
||||
You can also use the <code class="classname">EntityStore</code> to
|
||||
retrieve all the primary and secondary indexes related to a given type of entity
|
||||
object contained in the store. See <a class="xref" href="persist_index.html" title="Chapter 4. Working with Indices">Working with Indices</a> for
|
||||
more information.
|
||||
</p>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="persist-open"></a>Opening and Closing Environments and Stores</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
As described in
|
||||
<span>
|
||||
<a class="xref" href="env.html" title="Chapter 2. Database Environments">Database Environments</a>,
|
||||
</span>
|
||||
|
||||
|
||||
an
|
||||
<span class="emphasis"><em>environment</em></span> is a unit of
|
||||
encapsulation for JE databases. It also provides a
|
||||
handle by which activities common across the databases
|
||||
can be managed.
|
||||
</p>
|
||||
<p>
|
||||
To use an entity store, you must first open an environment and then provide that
|
||||
environment handle to the <code class="classname">EntityStore</code> constructor.
|
||||
</p>
|
||||
<p>
|
||||
For example, the following code fragment configures both
|
||||
the environment and the entity store such that they can
|
||||
be created if they do not exist. Both the environment and
|
||||
the entity store are then opened.
|
||||
</p>
|
||||
<pre class="programlisting">package persist.gettingStarted;
|
||||
|
||||
import java.io.File;
|
||||
|
||||
import com.sleepycat.je.DatabaseException;
|
||||
import com.sleepycat.je.Environment;
|
||||
import com.sleepycat.je.EnvironmentConfig;
|
||||
|
||||
import com.sleepycat.persist.EntityStore;
|
||||
import com.sleepycat.persist.StoreConfig;
|
||||
|
||||
...
|
||||
|
||||
private Environment myEnv;
|
||||
private EntityStore store;
|
||||
|
||||
try {
|
||||
EnvironmentConfig myEnvConfig = new EnvironmentConfig();
|
||||
StoreConfig storeConfig = new StoreConfig();
|
||||
|
||||
myEnvConfig.setAllowCreate(!readOnly);
|
||||
storeConfig.setAllowCreate(!readOnly);
|
||||
|
||||
// Open the environment and entity store
|
||||
myEnv = new Environment(envHome, myEnvConfig);
|
||||
store = new EntityStore(myEnv, "EntityStore", storeConfig);
|
||||
} catch(DatabaseException dbe) {
|
||||
System.err.println("Error opening environment and store: " +
|
||||
dbe.toString());
|
||||
System.exit(-1);
|
||||
} </pre>
|
||||
<p>
|
||||
As always, before you exit your program you should close both
|
||||
your store and your environment. It is recommended that you close your store before you close your
|
||||
environment.
|
||||
</p>
|
||||
<pre class="programlisting">if (store != null) {
|
||||
try {
|
||||
store.close();
|
||||
} catch(DatabaseException dbe) {
|
||||
System.err.println("Error closing store: " +
|
||||
dbe.toString());
|
||||
System.exit(-1);
|
||||
}
|
||||
}
|
||||
|
||||
if (myEnv != null) {
|
||||
try {
|
||||
// Finally, close environment.
|
||||
myEnv.close();
|
||||
} catch(DatabaseException dbe) {
|
||||
System.err.println("Error closing MyDbEnv: " +
|
||||
dbe.toString());
|
||||
System.exit(-1);
|
||||
}
|
||||
} </pre>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="dpl.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="dpl.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="persistobject.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Part I. Programming with the Direct Persistence Layer </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Persistent Objects</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
245
docs/GettingStartedGuide/persist_index.html
Normal file
245
docs/GettingStartedGuide/persist_index.html
Normal file
|
|
@ -0,0 +1,245 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Chapter 4. Working with Indices</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="dpl.html" title="Part I. Programming with the Direct Persistence Layer" />
|
||||
<link rel="prev" href="saveret.html" title="Saving and Retrieving Data" />
|
||||
<link rel="next" href="dplindexcreate.html" title="Creating Indexes" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Chapter 4. Working with Indices</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="saveret.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Part I. Programming with the Direct Persistence Layer</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="dplindexcreate.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="chapter" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title"><a id="persist_index"></a>Chapter 4. Working with Indices</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="toc">
|
||||
<p>
|
||||
<b>Table of Contents</b>
|
||||
</p>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="persist_index.html#dplindexaccess">Accessing Indexes</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="persist_index.html#primaryindexaccess">Accessing Primary Indices</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="persist_index.html#secondaryindexaccess">Accessing Secondary Indices</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="dplindexcreate.html">Creating Indexes</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="dplindexcreate.html#dplprimaryidxdecl">Declaring Primary Indexes</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="dplindexcreate.html#dplsecondaryidxdecl">Declaring Secondary Indexes</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="dplindexcreate.html#foreignkey">Foreign Key Constraints</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
</dl>
|
||||
</div>
|
||||
<p>
|
||||
All entity classes stored in JE using the DPL must have a
|
||||
primary index, or key, identified for them. All such classes may
|
||||
also have one or more secondary keys declared for them. This
|
||||
chapter describes primary and secondary indexes in detail, and
|
||||
shows how to access the indexes created for a given entity class.
|
||||
</p>
|
||||
<p>
|
||||
One way to organize access to your primary and secondary
|
||||
indexes is to create a <span class="emphasis"><em>data accessor</em></span>
|
||||
class. We show an implementation of a data accessor class in
|
||||
<a class="xref" href="simpleda.html" title="SimpleDA.class">SimpleDA.class</a>.
|
||||
</p>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="dplindexaccess"></a>Accessing Indexes</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="toc">
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="persist_index.html#primaryindexaccess">Accessing Primary Indices</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="persist_index.html#secondaryindexaccess">Accessing Secondary Indices</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</div>
|
||||
<p>
|
||||
In order to retrieve any object from an entity store, you
|
||||
must access at least the primary index for that object.
|
||||
Different entity classes stored in an entity store can have
|
||||
different primary indexes, but all entity classes must have a
|
||||
primary index declared for it. The primary index is just
|
||||
the default index used for the class. (That is, it is the
|
||||
data's primary <span class="emphasis"><em>key</em></span> for the underlying database.)
|
||||
</p>
|
||||
<p>
|
||||
Entity classes can optionally have secondary indexes
|
||||
declared for them. In order to access these secondary
|
||||
indexes, you must first access the primary index.
|
||||
</p>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="primaryindexaccess"></a>Accessing Primary Indices</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
You retrieve a primary index using the
|
||||
<code class="methodname">EntityStore.getPrimaryIndex()</code>
|
||||
method. To do this, you indicate the index key type
|
||||
(that is, whether it is a String, Integer, and
|
||||
so forth) and the class of the entities stored
|
||||
in the index.
|
||||
</p>
|
||||
<p>
|
||||
For example, the following retrieves the
|
||||
primary index for an <code class="classname">Inventory</code>
|
||||
class (we provide an implementation of this class in
|
||||
<a class="xref" href="inventoryclass.html" title="Inventory.java">Inventory.java</a>).
|
||||
These index keys are of type <code class="classname">String</code>.
|
||||
</p>
|
||||
<pre class="programlisting">PrimaryIndex<String,Inventory> inventoryBySku =
|
||||
store.getPrimaryIndex(String.class, Inventory.class); </pre>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="secondaryindexaccess"></a>Accessing Secondary Indices</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
You retrieve a secondary index using the
|
||||
<code class="methodname">EntityStore.getSecondaryIndex()</code>
|
||||
method. Because secondary indices actually
|
||||
refer to a primary index somewhere in your data
|
||||
store, to access a secondary index you:
|
||||
</p>
|
||||
<div class="orderedlist">
|
||||
<ol type="1">
|
||||
<li>
|
||||
<p>
|
||||
Provide the primary index as
|
||||
returned by
|
||||
<code class="methodname">EntityStore.getPrimaryIndex()</code>.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Identify the key data type used by
|
||||
the secondary index
|
||||
(<code class="classname">String</code>,
|
||||
<code class="classname">Long</code>,
|
||||
and so forth).
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Identify the name of the
|
||||
secondary key field.
|
||||
When you declare the
|
||||
<code class="classname">SecondaryIndex</code>
|
||||
object, you identify the entity class
|
||||
to which the secondary index
|
||||
must refer.
|
||||
</p>
|
||||
</li>
|
||||
</ol>
|
||||
</div>
|
||||
<p>
|
||||
For example, the following first retrieves the
|
||||
primary index, and then uses that to retrieve a secondary
|
||||
index. The secondary key is held by the
|
||||
<code class="literal">itemName</code> field of the
|
||||
<code class="classname">Inventory</code> class.
|
||||
</p>
|
||||
<pre class="programlisting">PrimaryIndex<String,Inventory> inventoryBySku =
|
||||
store.getPrimaryIndex(String.class, Inventory.class);
|
||||
|
||||
SecondaryIndex<String,String,Inventory> inventoryByName =
|
||||
store.getSecondaryIndex(inventoryBySku, String.class, "itemName"); </pre>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="saveret.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="dpl.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="dplindexcreate.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Saving and Retrieving Data </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Creating Indexes</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
147
docs/GettingStartedGuide/persistobject.html
Normal file
147
docs/GettingStartedGuide/persistobject.html
Normal file
|
|
@ -0,0 +1,147 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Persistent Objects</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="persist_first.html" title="Chapter 3. Direct Persistence Layer First Steps" />
|
||||
<link rel="prev" href="persist_first.html" title="Chapter 3. Direct Persistence Layer First Steps" />
|
||||
<link rel="next" href="saveret.html" title="Saving and Retrieving Data" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Persistent Objects</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="persist_first.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 3. Direct Persistence Layer First Steps</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="saveret.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="persistobject"></a>Persistent Objects</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
When using the DPL, you store data in the underlying
|
||||
JE databases by making objects
|
||||
<span class="emphasis"><em>persistent</em></span>. You do this using Java
|
||||
annotations that both identify the type of persistent
|
||||
object you are declaring, as well as the primary and
|
||||
secondary indices.
|
||||
</p>
|
||||
<p>
|
||||
The following are the annotations you will use with your
|
||||
DPL persistent classes:
|
||||
</p>
|
||||
<div class="informaltable">
|
||||
<table border="1" width="80%">
|
||||
<colgroup>
|
||||
<col />
|
||||
<col />
|
||||
</colgroup>
|
||||
<thead>
|
||||
<tr>
|
||||
<th>Annotation</th>
|
||||
<th>Description</th>
|
||||
</tr>
|
||||
</thead>
|
||||
<tbody>
|
||||
<tr>
|
||||
<td>@Entity</td>
|
||||
<td>
|
||||
Declares an entity class; that is, a class with a primary index
|
||||
and optionally one or more indices.
|
||||
</td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td>@Persistent</td>
|
||||
<td>
|
||||
Declares a persistent class; that is, a class used by an entity
|
||||
class. They do not have indices but instead are are stored or
|
||||
retrieved when an entity class makes direct use of them.
|
||||
</td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td>@PrimaryKey</td>
|
||||
<td>
|
||||
Declares a specific data member in an entity class to be the
|
||||
primary key for that object. This annotation must be used one
|
||||
and only one time for every entity class.
|
||||
</td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td>@SecondaryKey</td>
|
||||
<td>
|
||||
Declares a specific data member in an entity class to be a
|
||||
secondary key for that object. This annotation is optional, and
|
||||
can be used multiple times for an entity class.
|
||||
</td>
|
||||
</tr>
|
||||
</tbody>
|
||||
</table>
|
||||
</div>
|
||||
<p>
|
||||
For example, the following is declared to be an entity class:
|
||||
</p>
|
||||
<pre class="programlisting">package persist.gettingStarted;
|
||||
|
||||
import com.sleepycat.persist.model.Entity;
|
||||
import com.sleepycat.persist.model.PrimaryKey;
|
||||
|
||||
@Entity
|
||||
public class ExampleEntity {
|
||||
|
||||
// The primary key must be unique in the database.
|
||||
@PrimaryKey
|
||||
private String aPrimaryKey;
|
||||
|
||||
@SecondaryKey(relate=MANY_TO_ONE)
|
||||
private String aSecondaryKey;
|
||||
|
||||
...
|
||||
|
||||
// The remainder of the class' implementation is purposefully
|
||||
// omitted in the interest of brevity.
|
||||
|
||||
...
|
||||
} </pre>
|
||||
<p>
|
||||
We discuss primary and secondary keys in more detail in <a class="xref" href="persist_index.html" title="Chapter 4. Working with Indices">Working with Indices</a>.
|
||||
</p>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="persist_first.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="persist_first.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="saveret.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Chapter 3. Direct Persistence Layer First Steps </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Saving and Retrieving Data</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
174
docs/GettingStartedGuide/preface.html
Normal file
174
docs/GettingStartedGuide/preface.html
Normal file
|
|
@ -0,0 +1,174 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Preface</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="prev" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="next" href="moreinfo.html" title="For More Information" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Preface</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="index.html">Prev</a> </td>
|
||||
<th width="60%" align="center"> </th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="moreinfo.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="preface" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title"><a id="preface"></a>Preface</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="toc">
|
||||
<p>
|
||||
<b>Table of Contents</b>
|
||||
</p>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="preface.html#conventions">Conventions Used in this Book</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="moreinfo.html">For More Information</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="moreinfo.html#contact_us">Contact Us</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
</dl>
|
||||
</div>
|
||||
<p>
|
||||
Welcome to Berkeley DB Java Edition (JE).
|
||||
|
||||
<span>
|
||||
This document introduces JE, version 12<span class="emphasis"><em>c</em></span> Release 2.
|
||||
</span>
|
||||
|
||||
</p>
|
||||
<p>
|
||||
This document is intended to provide a rapid introduction
|
||||
to the JE API set and related concepts. The goal of this
|
||||
document is to provide you with an efficient mechanism with which
|
||||
you can evaluate JE against your project's technical
|
||||
requirements. As such, this document is intended for
|
||||
<span>Java</span>
|
||||
|
||||
|
||||
developers and senior software architects who are looking for an
|
||||
<span>
|
||||
in-process data management solution.
|
||||
</span>
|
||||
|
||||
No prior experience with Berkeley DB Java Edition is expected or required.
|
||||
</p>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="conventions"></a>Conventions Used in this Book</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
The following typographical conventions are used within in this manual:
|
||||
</p>
|
||||
<p>
|
||||
Class names are represented in <code class="classname">monospaced font</code>, as are <code class="methodname">method
|
||||
names</code>. For example:
|
||||
|
||||
<span>"The <code class="methodname">Environment.openDatabase()</code> method
|
||||
returns a <code class="classname">Database</code> class object."</span>
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
</p>
|
||||
<p>
|
||||
Variable or non-literal text is presented in <span class="emphasis"><em>italics</em></span>. For example: "Go to your
|
||||
<span class="emphasis"><em>JE_HOME</em></span>
|
||||
|
||||
|
||||
directory."
|
||||
</p>
|
||||
<p>
|
||||
Program examples are displayed in a <code class="classname">monospaced font</code> on a shaded background.
|
||||
For example:
|
||||
</p>
|
||||
<pre class="programlisting">import com.sleepycat.je.Environment;
|
||||
|
||||
...
|
||||
|
||||
// Open the environment. Allow it to be created if it does not
|
||||
// already exist.
|
||||
Environment myDbEnv;</pre>
|
||||
<p>
|
||||
In some situations, programming examples are updated from one chapter to the next. When
|
||||
this occurs, the new code is presented in <strong class="userinput"><code>monospaced bold</code></strong> font. For example:
|
||||
</p>
|
||||
<pre class="programlisting">import com.sleepycat.je.Environment;
|
||||
<strong class="userinput"><code>import com.sleepycat.je.EnvironmentConfig;
|
||||
import java.io.File;</code></strong>
|
||||
|
||||
...
|
||||
|
||||
// Open the environment. Allow it to be created if it does not
|
||||
// already exist.
|
||||
Environment myDbEnv;
|
||||
<strong class="userinput"><code>EnvironmentConfig envConfig = new EnvironmentConfig();
|
||||
envConfig.setAllowCreate(true);
|
||||
myDbEnv = new Environment(new File("/export/dbEnv"), envConfig);</code></strong> </pre>
|
||||
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
|
||||
<h3 class="title">Note</h3>
|
||||
<p>
|
||||
Finally, notes of interest are represented using a note block such
|
||||
as this.
|
||||
</p>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="index.html">Prev</a> </td>
|
||||
<td width="20%" align="center"> </td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="moreinfo.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Getting Started with Berkeley DB Java Edition </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> For More Information</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
125
docs/GettingStartedGuide/readSecondary.html
Normal file
125
docs/GettingStartedGuide/readSecondary.html
Normal file
|
|
@ -0,0 +1,125 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Reading Secondary Databases</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="indexes.html" title="Chapter 10. Secondary Databases" />
|
||||
<link rel="prev" href="secondaryProps.html" title="Secondary Database Properties" />
|
||||
<link rel="next" href="secondaryDelete.html" title="Deleting Secondary Database Records" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Reading Secondary Databases</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="secondaryProps.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 10. Secondary Databases</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="secondaryDelete.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="readSecondary"></a>Reading Secondary Databases</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
Like a primary database, you can read records from your secondary
|
||||
database either by using the
|
||||
<span>
|
||||
<code class="methodname">SecondaryDatabase.get()</code> method,
|
||||
</span>
|
||||
|
||||
or by using
|
||||
<span>a <code class="classname">SecondaryCursor</code>.</span>
|
||||
|
||||
|
||||
The main difference between reading secondary and primary databases is that when
|
||||
you read a secondary database record, the secondary record's data is not
|
||||
returned to you. Instead, the primary key and data corresponding to the
|
||||
secondary key are returned to you.
|
||||
</p>
|
||||
<p>
|
||||
For example, assuming your secondary database contains keys related
|
||||
to a person's full name:
|
||||
</p>
|
||||
<a id="je_index6"></a>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.je.DatabaseEntry;
|
||||
import com.sleepycat.je.LockMode;
|
||||
import com.sleepycat.je.OperationStatus;
|
||||
import com.sleepycat.je.SecondaryDatabase;
|
||||
|
||||
...
|
||||
try {
|
||||
// Omitting all database and environment opens
|
||||
...
|
||||
|
||||
String searchName = "John Doe";
|
||||
DatabaseEntry searchKey =
|
||||
new DatabaseEntry(searchName.getBytes("UTF-8"));
|
||||
DatabaseEntry primaryKey = new DatabaseEntry();
|
||||
DatabaseEntry primaryData = new DatabaseEntry();
|
||||
|
||||
// Get the primary key and data for the user 'John Doe'.
|
||||
OperationStatus retVal = mySecondaryDatabase.get(null, searchKey,
|
||||
primaryKey,
|
||||
primaryData,
|
||||
LockMode.DEFAULT);
|
||||
} catch (Exception e) {
|
||||
// Exception handling goes here
|
||||
}</pre>
|
||||
<p>
|
||||
Note that, just like
|
||||
<span><code class="methodname">Database.get()</code>, </span>
|
||||
|
||||
|
||||
if your secondary database supports duplicate records then
|
||||
<code class="methodname">SecondaryDatabase.get()</code>
|
||||
|
||||
only return the first record found in a matching duplicates set. If you
|
||||
want to see all the records related to a specific secondary key, then use a
|
||||
<span>
|
||||
<code class="classname">SecondaryCursor</code> (described in <a class="xref" href="secondaryCursor.html" title="Using Secondary Cursors">
|
||||
<span>Using Secondary Cursors</span>
|
||||
|
||||
</a>).
|
||||
</span>
|
||||
|
||||
</p>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="secondaryProps.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="indexes.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="secondaryDelete.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Secondary Database Properties </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Deleting Secondary Database Records</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
103
docs/GettingStartedGuide/restore.html
Normal file
103
docs/GettingStartedGuide/restore.html
Normal file
|
|
@ -0,0 +1,103 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>JE Backup and Restore</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="introduction.html" title="Chapter 1. Introduction to Berkeley DB Java Edition" />
|
||||
<link rel="prev" href="applicationoverview.html" title="The JE Application" />
|
||||
<link rel="next" href="jca.html" title="JCA Support" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">JE Backup and Restore</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="applicationoverview.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 1. Introduction to Berkeley DB Java Edition </th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="jca.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="restore"></a>JE Backup and Restore</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
To backup your database, copy the log files (the
|
||||
<code class="literal">.jdb</code> files) starting from the lowest
|
||||
numbered log file to the highest numbered log file to your
|
||||
backup media. Be sure to copy the bytes of the individual
|
||||
database files in order from the lowest to the highest. You do
|
||||
not have to close your database or otherwise cease database
|
||||
operations when you do this.
|
||||
</p>
|
||||
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
|
||||
<h3 class="title">Note</h3>
|
||||
<p>
|
||||
Note that if you are using subdirectories to store your log
|
||||
files, then you should copy those subdirectories and their
|
||||
contents instead of simply copying individual files.
|
||||
Multiple subdirectories can be used to improve JE
|
||||
throughput, but this feature is not turned on by default.
|
||||
See <a class="xref" href="env.html#multisubdir" title="Multiple Environment Subdirectories">Multiple Environment Subdirectories</a>
|
||||
for information on how to configure this feature.
|
||||
</p>
|
||||
</div>
|
||||
<p>
|
||||
Restoring a JE database from a backup consists of closing your
|
||||
JE environment, copying archived log files back into your
|
||||
environment directory and then opening your JE environment
|
||||
again. If you are using subdirectories to store your log files,
|
||||
then make sure to copy those subdirectories back into the
|
||||
environment home directory, and make sure the same log files are in
|
||||
each subdirectory as was there when you took the backup.
|
||||
</p>
|
||||
<p>
|
||||
Note that whenever a JE environment is opened, JE runs
|
||||
<span class="emphasis"><em>normal recovery</em></span>. This involves bringing your
|
||||
database into a consistent state given the changed data found in the
|
||||
database. If you are using transactions during normal operations, then
|
||||
JE automatically runs checkpoints for you so as to limit the time
|
||||
required to run this recovery. In any case, running normal recovery is a
|
||||
routine operation, while performing database restores is not.
|
||||
</p>
|
||||
<p>
|
||||
For more information on JE backup and restores, and on checkpoints, see
|
||||
<a class="xref" href="backuprestore.html" title="Chapter 11. Backing up and Restoring Berkeley DB Java Edition Applications">Backing up and Restoring Berkeley DB Java Edition Applications</a>.
|
||||
</p>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="applicationoverview.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="introduction.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="jca.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">The JE Application </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> JCA Support</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
123
docs/GettingStartedGuide/saveret.html
Normal file
123
docs/GettingStartedGuide/saveret.html
Normal file
|
|
@ -0,0 +1,123 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Saving and Retrieving Data</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="persist_first.html" title="Chapter 3. Direct Persistence Layer First Steps" />
|
||||
<link rel="prev" href="persistobject.html" title="Persistent Objects" />
|
||||
<link rel="next" href="persist_index.html" title="Chapter 4. Working with Indices" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Saving and Retrieving Data</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="persistobject.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 3. Direct Persistence Layer First Steps</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="persist_index.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="saveret"></a>Saving and Retrieving Data</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
All data stored using the DPL has one primary index and
|
||||
zero or more secondary indices associated with it.
|
||||
(Sometimes these are referred to as the primary and
|
||||
secondary <span class="emphasis"><em>keys</em></span>.) So to store data under the DPL, you must:
|
||||
</p>
|
||||
<div class="orderedlist">
|
||||
<ol type="1">
|
||||
<li>
|
||||
<p>
|
||||
Declare a class to be an entity class.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Identify the features on the class which
|
||||
represent indexed material.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Retrieve the store's primary index for a
|
||||
given class using the
|
||||
<code class="methodname">EntityStore.getPrimaryIndex()</code>
|
||||
method.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Put class objects to the store using the
|
||||
<code class="methodname">PrimaryIndex.put()</code>
|
||||
method.
|
||||
</p>
|
||||
</li>
|
||||
</ol>
|
||||
</div>
|
||||
<p>
|
||||
In order to retrieve an object from the store, you use
|
||||
the index that is most convenient for your purpose. This
|
||||
may be the primary index, or it may be some other
|
||||
secondary index that you declared on your entity class.
|
||||
</p>
|
||||
<p>
|
||||
You obtain a primary index in the same was as when you
|
||||
put the object to the store: using
|
||||
<code class="methodname">EntityStore.getPrimaryIndex()</code>.
|
||||
You can get a secondary index for the store using the
|
||||
<code class="methodname">EntityStore.getSecondaryIndex()</code>
|
||||
method. Note that
|
||||
<code class="methodname">getSecondaryIndex()</code> requires you
|
||||
to provide a <code class="classname">PrimaryIndex</code> class
|
||||
instance when you call it, so a class's primary index is
|
||||
always required when retrieving objects from an entity
|
||||
store.
|
||||
</p>
|
||||
<p>
|
||||
Usually all of the activity surrounding saving and
|
||||
retrieving data is organized within a class or classes
|
||||
specialized to that purpose. We describe the construction
|
||||
of these data accessor classes in <a class="xref" href="simpleda.html" title="SimpleDA.class">SimpleDA.class</a>. But before you perform
|
||||
any entity store activity, you need to understand
|
||||
indexes. We therefore describe them in the next chapter.
|
||||
</p>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="persistobject.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="persist_first.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="persist_index.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Persistent Objects </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Chapter 4. Working with Indices</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
155
docs/GettingStartedGuide/secondaryCursor.html
Normal file
155
docs/GettingStartedGuide/secondaryCursor.html
Normal file
|
|
@ -0,0 +1,155 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Using Secondary Cursors</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="indexes.html" title="Chapter 10. Secondary Databases" />
|
||||
<link rel="prev" href="secondaryDelete.html" title="Deleting Secondary Database Records" />
|
||||
<link rel="next" href="joins.html" title="Database Joins" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">
|
||||
<span xmlns="http://www.w3.org/1999/xhtml">Using Secondary Cursors</span>
|
||||
|
||||
</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="secondaryDelete.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 10. Secondary Databases</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="joins.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="secondaryCursor"></a>
|
||||
<span>Using Secondary Cursors</span>
|
||||
|
||||
</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
Just like cursors on a primary database, you can use
|
||||
<span>secondary cursors</span>
|
||||
|
||||
to iterate over the records in a secondary database. Like
|
||||
|
||||
<span>normal cursors,</span>
|
||||
|
||||
|
||||
you can also use
|
||||
<span>secondary cursors</span>
|
||||
|
||||
to search for specific records in a database, to seek to the first
|
||||
or last record in the database, to get the next duplicate record,
|
||||
<span>to get the next non-duplicate record,</span>
|
||||
and so forth. For a complete description on cursors and their capabilities, see
|
||||
<a class="xref" href="Cursors.html" title="Chapter 9. Using Cursors">Using Cursors</a>.
|
||||
</p>
|
||||
<p>
|
||||
However, when you use
|
||||
<span>secondary cursors:</span>
|
||||
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
Any data returned is the data contained on the primary database
|
||||
record referenced by the secondary record.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="methodname">SecondaryCursor.getSearchBoth()</code> and
|
||||
related methods do not search based on a key/data pair. Instead, you
|
||||
search based on a secondary key and a primary key. The data returned
|
||||
is the primary data that most closely matches the two keys provided
|
||||
for the search.
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<p>
|
||||
For example, suppose you are using the databases, classes, and key
|
||||
<span>creators</span>
|
||||
|
||||
described in <a class="xref" href="keyCreator.html" title="Implementing Key Creators">Implementing Key
|
||||
<span>Creators</span>
|
||||
|
||||
</a>.
|
||||
Then the following searches for a person's
|
||||
name in the secondary database, and deletes all secondary and primary
|
||||
records that use that name.
|
||||
</p>
|
||||
<a id="je_index8"></a>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.je.DatabaseEntry;
|
||||
import com.sleepycat.je.LockMode;
|
||||
import com.sleepycat.je.OperationStatus;
|
||||
import com.sleepycat.je.SecondaryDatabase;
|
||||
import com.sleepycat.je.SecondaryCursor;
|
||||
|
||||
...
|
||||
try {
|
||||
// Database and environment opens omitted for brevity
|
||||
...
|
||||
|
||||
String secondaryName = "John Doe";
|
||||
DatabaseEntry secondaryKey =
|
||||
new DatabaseEntry(secondaryName.getBytes("UTF-8"));
|
||||
|
||||
DatabaseEntry foundData = new DatabaseEntry();
|
||||
|
||||
SecondaryCursor mySecCursor =
|
||||
mySecondaryDatabase.openSecondaryCursor(null, null);
|
||||
|
||||
OperationStatus retVal = mySecCursor.getSearchKey(secondaryKey,
|
||||
foundData,
|
||||
LockMode.DEFAULT);
|
||||
while (retVal == OperationStatus.SUCCESS) {
|
||||
mySecCursor.delete();
|
||||
retVal = mySecCursor.getNextDup(secondaryKey,
|
||||
foundData,
|
||||
LockMode.DEFAULT);
|
||||
}
|
||||
} catch (Exception e) {
|
||||
// Exception handling goes here
|
||||
}</pre>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="secondaryDelete.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="indexes.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="joins.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Deleting Secondary Database Records </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Database Joins</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
128
docs/GettingStartedGuide/secondaryDelete.html
Normal file
128
docs/GettingStartedGuide/secondaryDelete.html
Normal file
|
|
@ -0,0 +1,128 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Deleting Secondary Database Records</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="indexes.html" title="Chapter 10. Secondary Databases" />
|
||||
<link rel="prev" href="readSecondary.html" title="Reading Secondary Databases" />
|
||||
<link rel="next" href="secondaryCursor.html" title="Using Secondary Cursors" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Deleting Secondary Database Records</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="readSecondary.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 10. Secondary Databases</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="secondaryCursor.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="secondaryDelete"></a>Deleting Secondary Database Records</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
In general, you
|
||||
<span>can</span>
|
||||
|
||||
not modify a secondary database directly. In
|
||||
order to modify a secondary database, you should modify the primary
|
||||
database and simply allow JE to manage the secondary modifications for you.
|
||||
</p>
|
||||
<p>
|
||||
However, as a convenience, you can delete
|
||||
<code class="classname">SecondaryDatabase</code>
|
||||
|
||||
records directly. Doing so causes the associated primary key/data pair to be deleted.
|
||||
This in turn causes JE to delete all
|
||||
<code class="classname">SecondaryDatabase</code>
|
||||
|
||||
records that reference the primary record.
|
||||
</p>
|
||||
<p>
|
||||
You can use the
|
||||
<code class="methodname">SecondaryDatabase.delete()</code>
|
||||
|
||||
|
||||
method to delete a secondary database record. Note that if your
|
||||
|
||||
<code class="classname">SecondaryDatabase</code>
|
||||
contains duplicate records, then deleting a record from the set of
|
||||
duplicates causes all of the duplicates to be deleted as well.
|
||||
|
||||
</p>
|
||||
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
|
||||
<h3 class="title">Note</h3>
|
||||
<p>
|
||||
<span><code class="methodname">SecondaryDatabase.delete()</code> causes the
|
||||
previously described delete operations to occur
|
||||
</span>
|
||||
|
||||
only if the primary database is opened for write access.
|
||||
</p>
|
||||
</div>
|
||||
<p>For example:</p>
|
||||
<a id="je_index7"></a>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.je.DatabaseEntry;
|
||||
import com.sleepycat.je.DatabaseException;
|
||||
import com.sleepycat.je.OperationStatus;
|
||||
import com.sleepycat.je.SecondaryDatabase;
|
||||
|
||||
...
|
||||
try {
|
||||
// Omitting all database and environment opens
|
||||
...
|
||||
|
||||
String searchName = "John Doe";
|
||||
DatabaseEntry searchKey =
|
||||
new DatabaseEntry(searchName.getBytes("UTF-8"));
|
||||
|
||||
// Delete the first secondary record that uses "John Doe" as
|
||||
// a key. This causes the primary record referenced by this secondary
|
||||
// record to be deleted.
|
||||
OperationStatus retVal = mySecondaryDatabase.delete(null, searchKey);
|
||||
} catch (Exception e) {
|
||||
// Exception handling goes here
|
||||
}</pre>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="readSecondary.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="indexes.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="secondaryCursor.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Reading Secondary Databases </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top">
|
||||
<span>Using Secondary Cursors</span>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
94
docs/GettingStartedGuide/secondaryProps.html
Normal file
94
docs/GettingStartedGuide/secondaryProps.html
Normal file
|
|
@ -0,0 +1,94 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Secondary Database Properties</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="indexes.html" title="Chapter 10. Secondary Databases" />
|
||||
<link rel="prev" href="keyCreator.html" title="Implementing Key Creators" />
|
||||
<link rel="next" href="readSecondary.html" title="Reading Secondary Databases" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Secondary Database Properties</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="keyCreator.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 10. Secondary Databases</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="readSecondary.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="secondaryProps"></a>Secondary Database Properties</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>Secondary databases accept <code class="classname">SecondaryConfig</code>
|
||||
objects. <code class="classname">SecondaryConfig</code> is a subclass of <code class="classname">DatabaseConfig</code>,
|
||||
so it can manage all of the same properties as does <code class="classname">DatabaseConfig</code>.
|
||||
See <a class="xref" href="dbprops.html" title="Database Properties">Database Properties</a> for more information.</p>
|
||||
<p>In addition to the <code class="classname">DatabaseConfig</code> properties,
|
||||
<code class="classname">SecondaryConfig</code> also allows you to manage the following properties:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
<code class="methodname">SecondaryConfig.setAllowPopulate()</code>
|
||||
</p>
|
||||
<p>If true, the secondary database can be auto-populated. This means
|
||||
that on open, if the secondary database is empty then the primary
|
||||
database is read in its entirety and additions/modifications to the
|
||||
secondary's records occur automatically.</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="methodname">SecondaryConfig.setKeyCreator()</code>
|
||||
</p>
|
||||
<p>Identifies the key creator object to be used for secondary key
|
||||
creation. See <a class="xref" href="keyCreator.html" title="Implementing Key Creators">Implementing Key
|
||||
<span>Creators</span>
|
||||
|
||||
</a>
|
||||
for more information.</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="keyCreator.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="indexes.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="readSecondary.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Implementing Key
|
||||
<span>Creators</span>
|
||||
|
||||
</td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Reading Secondary Databases</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
104
docs/GettingStartedGuide/simpleda.html
Normal file
104
docs/GettingStartedGuide/simpleda.html
Normal file
|
|
@ -0,0 +1,104 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>SimpleDA.class</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="persist_access.html" title="Chapter 5. Saving and Retrieving Objects" />
|
||||
<link rel="prev" href="persist_access.html" title="Chapter 5. Saving and Retrieving Objects" />
|
||||
<link rel="next" href="simpleput.html" title="Placing Objects in an Entity Store" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">SimpleDA.class</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="persist_access.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 5. Saving and Retrieving Objects</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="simpleput.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="simpleda"></a>SimpleDA.class</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
As mentioned above, we organize our primary and
|
||||
secondary indexes using a specialize data
|
||||
accessor class. The main reason for this class
|
||||
to exist is to provide convenient access to all
|
||||
the indexes in use for our entity class (see
|
||||
the previous section, <a class="xref" href="persist_access.html#simpleentity" title="A Simple Entity Class">A Simple Entity Class</a>, for that
|
||||
implementation).
|
||||
</p>
|
||||
<p>
|
||||
For a description on retrieving primary and
|
||||
secondary indexes under the DPL, see
|
||||
<a class="xref" href="persist_index.html" title="Chapter 4. Working with Indices">Working with Indices</a>
|
||||
</p>
|
||||
<pre class="programlisting">package persist.gettingStarted;
|
||||
|
||||
import java.io.File;
|
||||
|
||||
import com.sleepycat.je.DatabaseException;
|
||||
import com.sleepycat.persist.EntityStore;
|
||||
import com.sleepycat.persist.PrimaryIndex;
|
||||
import com.sleepycat.persist.SecondaryIndex;
|
||||
|
||||
public class SimpleDA {
|
||||
// Open the indices
|
||||
public SimpleDA(EntityStore store)
|
||||
throws DatabaseException {
|
||||
|
||||
// Primary key for SimpleEntityClass classes
|
||||
pIdx = store.getPrimaryIndex(
|
||||
String.class, SimpleEntityClass.class);
|
||||
|
||||
// Secondary key for SimpleEntityClass classes
|
||||
// Last field in the getSecondaryIndex() method must be
|
||||
// the name of a class member; in this case, an
|
||||
// SimpleEntityClass.class data member.
|
||||
sIdx = store.getSecondaryIndex(
|
||||
pIdx, String.class, "sKey");
|
||||
}
|
||||
|
||||
// Index Accessors
|
||||
PrimaryIndex<String,SimpleEntityClass> pIdx;
|
||||
SecondaryIndex<String,String,SimpleEntityClass> sIdx;
|
||||
} </pre>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="persist_access.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="persist_access.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="simpleput.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Chapter 5. Saving and Retrieving Objects </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Placing Objects in an Entity Store</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
170
docs/GettingStartedGuide/simpleget.html
Normal file
170
docs/GettingStartedGuide/simpleget.html
Normal file
|
|
@ -0,0 +1,170 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Retrieving Objects from an Entity Store</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="persist_access.html" title="Chapter 5. Saving and Retrieving Objects" />
|
||||
<link rel="prev" href="simpleput.html" title="Placing Objects in an Entity Store" />
|
||||
<link rel="next" href="getmultiple.html" title="Retrieving Multiple Objects" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Retrieving Objects from an Entity Store</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="simpleput.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 5. Saving and Retrieving Objects</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="getmultiple.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="simpleget"></a>Retrieving Objects from an Entity Store</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
You retrieve objects placed in an entity store by using
|
||||
either the object's primary index, or the appropriate
|
||||
secondary index if it exists. The following application
|
||||
illustrates this by retrieving some of the objects that
|
||||
we placed in an entity store in the previous section.
|
||||
</p>
|
||||
<p>
|
||||
To begin, we import the Java classes that our example
|
||||
needs. We also instantiate the private data members that we
|
||||
require.
|
||||
</p>
|
||||
<pre class="programlisting">package persist.gettingStarted;
|
||||
|
||||
import java.io.File;
|
||||
|
||||
import com.sleepycat.je.DatabaseException;
|
||||
import com.sleepycat.je.Environment;
|
||||
import com.sleepycat.je.EnvironmentConfig;
|
||||
|
||||
import com.sleepycat.persist.EntityStore;
|
||||
import com.sleepycat.persist.StoreConfig;
|
||||
|
||||
public class SimpleStoreGet {
|
||||
|
||||
private static File envHome = new File("./JEDB");
|
||||
|
||||
private Environment envmnt;
|
||||
private EntityStore store;
|
||||
private SimpleDA sda; </pre>
|
||||
<p>
|
||||
Next we create a method that simply opens our database
|
||||
environment and entity store for us.
|
||||
</p>
|
||||
<pre class="programlisting"> // The setup() method opens the environment and store
|
||||
// for us.
|
||||
public void setup()
|
||||
throws DatabaseException {
|
||||
|
||||
EnvironmentConfig envConfig = new EnvironmentConfig();
|
||||
StoreConfig storeConfig = new StoreConfig();
|
||||
|
||||
envConfig.setAllowCreate(true);
|
||||
storeConfig.setAllowCreate(true);
|
||||
|
||||
// Open the environment and entity store
|
||||
envmnt = new Environment(envHome, envConfig);
|
||||
store = new EntityStore(envmnt, "EntityStore", storeConfig);
|
||||
} </pre>
|
||||
<p>
|
||||
We also need a method to close our environment and store.
|
||||
</p>
|
||||
<pre class="programlisting"> // Close our environment and store.
|
||||
public void shutdown()
|
||||
throws DatabaseException {
|
||||
|
||||
store.close();
|
||||
envmnt.close();
|
||||
} </pre>
|
||||
<p>
|
||||
Now we retrieve a few objects. To do this, we instantiate a
|
||||
<code class="classname">SimpleDA</code> (see <a class="xref" href="simpleda.html" title="SimpleDA.class">SimpleDA.class</a>) class that we use to access
|
||||
our primary and secondary indexes. Then we retrieve objects
|
||||
based on a primary or secondary index value. And finally, we
|
||||
display the retrieved objects.
|
||||
</p>
|
||||
<pre class="programlisting"> // Retrieve some SimpleEntityClass objects from the store.
|
||||
private void run()
|
||||
throws DatabaseException {
|
||||
|
||||
setup();
|
||||
|
||||
// Open the data accessor. This is used to store
|
||||
// persistent objects.
|
||||
sda = new SimpleDA(store);
|
||||
|
||||
// Instantiate and store some entity classes
|
||||
SimpleEntityClass sec1 = sda.pIdx.get("keyone");
|
||||
SimpleEntityClass sec2 = sda.pIdx.get("keytwo");
|
||||
|
||||
SimpleEntityClass sec4 = sda.sIdx.get("skeythree");
|
||||
|
||||
System.out.println("sec1: " + sec1.getPKey());
|
||||
System.out.println("sec2: " + sec2.getPKey());
|
||||
System.out.println("sec4: " + sec4.getPKey());
|
||||
|
||||
|
||||
shutdown();
|
||||
} </pre>
|
||||
<p>
|
||||
Finally, to complete our class, we need a
|
||||
<code class="methodname">main()</code> method, which simply calls our
|
||||
<code class="methodname">run()</code> method.
|
||||
</p>
|
||||
<pre class="programlisting"> // main
|
||||
public static void main(String args[]) {
|
||||
SimpleStoreGet ssg = new SimpleStoreGet();
|
||||
try {
|
||||
ssg.run();
|
||||
} catch (DatabaseException dbe) {
|
||||
System.err.println("SimpleStoreGet: " + dbe.toString());
|
||||
dbe.printStackTrace();
|
||||
} catch (Exception e) {
|
||||
System.out.println("Exception: " + e.toString());
|
||||
e.printStackTrace();
|
||||
}
|
||||
System.out.println("All done.");
|
||||
}
|
||||
|
||||
} </pre>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="simpleput.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="persist_access.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="getmultiple.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Placing Objects in an Entity Store </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Retrieving Multiple Objects</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
229
docs/GettingStartedGuide/simpleput.html
Normal file
229
docs/GettingStartedGuide/simpleput.html
Normal file
|
|
@ -0,0 +1,229 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Placing Objects in an Entity Store</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="persist_access.html" title="Chapter 5. Saving and Retrieving Objects" />
|
||||
<link rel="prev" href="simpleda.html" title="SimpleDA.class" />
|
||||
<link rel="next" href="simpleget.html" title="Retrieving Objects from an Entity Store" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Placing Objects in an Entity Store</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="simpleda.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 5. Saving and Retrieving Objects</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="simpleget.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="simpleput"></a>Placing Objects in an Entity Store</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
In order to place an object in a DPL entity store,
|
||||
you must:
|
||||
</p>
|
||||
<div class="orderedlist">
|
||||
<ol type="1">
|
||||
<li>
|
||||
<p>
|
||||
Open the environment and store.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Instantiate the object.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Put the object to the store using the
|
||||
<code class="methodname">put()</code> method
|
||||
for the object's primary index.
|
||||
</p>
|
||||
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
|
||||
<h3 class="title">Note</h3>
|
||||
<p>
|
||||
A version of this method exists which allows you to
|
||||
specify a Time to Live value for the record that you are
|
||||
inserting. See <a class="xref" href="timetolive.html" title="Using Time to Live">Using Time to Live</a>
|
||||
for more information.
|
||||
</p>
|
||||
</div>
|
||||
</li>
|
||||
</ol>
|
||||
</div>
|
||||
<p>
|
||||
The following example uses the <code class="classname">SimpleDA</code>
|
||||
class that we show in <a class="xref" href="simpleda.html" title="SimpleDA.class">SimpleDA.class</a> to put a
|
||||
<code class="classname">SimpleEntityClass</code> object (see
|
||||
<a class="xref" href="persist_access.html#simpleentity" title="A Simple Entity Class">A Simple Entity Class</a>) to the
|
||||
entity store.
|
||||
</p>
|
||||
<p>
|
||||
To begin, we import the Java classes that our example
|
||||
needs. We also instantiate the private data members that we
|
||||
require.
|
||||
</p>
|
||||
<pre class="programlisting">package persist.gettingStarted;
|
||||
|
||||
import java.io.File;
|
||||
|
||||
import com.sleepycat.je.DatabaseException;
|
||||
import com.sleepycat.je.Environment;
|
||||
import com.sleepycat.je.EnvironmentConfig;
|
||||
|
||||
import com.sleepycat.persist.EntityStore;
|
||||
import com.sleepycat.persist.StoreConfig;
|
||||
|
||||
public class SimpleStorePut {
|
||||
|
||||
private static File envHome = new File("./JEDB");
|
||||
|
||||
private Environment envmnt;
|
||||
private EntityStore store;
|
||||
private SimpleDA sda; </pre>
|
||||
<p>
|
||||
Next we create a method that simply opens our database
|
||||
environment and entity store for us.
|
||||
</p>
|
||||
<pre class="programlisting"> // The setup() method opens the environment and store
|
||||
// for us.
|
||||
public void setup()
|
||||
throws DatabaseException {
|
||||
|
||||
EnvironmentConfig envConfig = new EnvironmentConfig();
|
||||
StoreConfig storeConfig = new StoreConfig();
|
||||
|
||||
envConfig.setAllowCreate(true);
|
||||
storeConfig.setAllowCreate(true);
|
||||
|
||||
// Open the environment and entity store
|
||||
envmnt = new Environment(envHome, envConfig);
|
||||
store = new EntityStore(envmnt, "EntityStore", storeConfig);
|
||||
} </pre>
|
||||
<p>
|
||||
We also need a method to close our environment and store.
|
||||
</p>
|
||||
<pre class="programlisting"> // Close our environment and store.
|
||||
public void shutdown()
|
||||
throws DatabaseException {
|
||||
|
||||
store.close();
|
||||
envmnt.close();
|
||||
} </pre>
|
||||
<p>
|
||||
Now we need to create a method to actually write objects to our
|
||||
store. This method creates a <code class="classname">SimpleDA</code>
|
||||
object (see <a class="xref" href="simpleda.html" title="SimpleDA.class">SimpleDA.class</a>) that we
|
||||
will use to access our indexes. Then we instantiate a series
|
||||
of <code class="classname">SimpleEntityClass</code> (see <a class="xref" href="persist_access.html#simpleentity" title="A Simple Entity Class">A Simple Entity Class</a>)
|
||||
objects that we
|
||||
will place in our store. Finally, we use our primary index
|
||||
(obtained from the <code class="classname">SimpleDA</code> class
|
||||
instance) to actually place these objects in our store.
|
||||
</p>
|
||||
<p>
|
||||
In <a class="xref" href="simpleget.html" title="Retrieving Objects from an Entity Store">Retrieving Objects from an Entity Store</a>
|
||||
we show a class that is used to retrieve these objects.
|
||||
</p>
|
||||
<pre class="programlisting"> // Populate the entity store
|
||||
private void run()
|
||||
throws DatabaseException {
|
||||
|
||||
setup();
|
||||
|
||||
// Open the data accessor. This is used to store
|
||||
// persistent objects.
|
||||
sda = new SimpleDA(store);
|
||||
|
||||
// Instantiate and store some entity classes
|
||||
SimpleEntityClass sec1 = new SimpleEntityClass();
|
||||
SimpleEntityClass sec2 = new SimpleEntityClass();
|
||||
SimpleEntityClass sec3 = new SimpleEntityClass();
|
||||
SimpleEntityClass sec4 = new SimpleEntityClass();
|
||||
SimpleEntityClass sec5 = new SimpleEntityClass();
|
||||
|
||||
sec1.setPKey("keyone");
|
||||
sec1.setSKey("skeyone");
|
||||
|
||||
sec2.setPKey("keytwo");
|
||||
sec2.setSKey("skeyone");
|
||||
|
||||
sec3.setPKey("keythree");
|
||||
sec3.setSKey("skeytwo");
|
||||
|
||||
sec4.setPKey("keyfour");
|
||||
sec4.setSKey("skeythree");
|
||||
|
||||
sec5.setPKey("keyfive");
|
||||
sec5.setSKey("skeyfour");
|
||||
|
||||
sda.pIdx.put(sec1);
|
||||
sda.pIdx.put(sec2);
|
||||
sda.pIdx.put(sec3);
|
||||
sda.pIdx.put(sec4);
|
||||
sda.pIdx.put(sec5);
|
||||
|
||||
shutdown();
|
||||
} </pre>
|
||||
<p>
|
||||
Finally, to complete our class, we need a
|
||||
<code class="methodname">main()</code> method, which simply calls our
|
||||
<code class="methodname">run()</code> method.
|
||||
</p>
|
||||
<pre class="programlisting"> // main
|
||||
public static void main(String args[]) {
|
||||
SimpleStorePut ssp = new SimpleStorePut();
|
||||
try {
|
||||
ssp.run();
|
||||
} catch (DatabaseException dbe) {
|
||||
System.err.println("SimpleStorePut: " + dbe.toString());
|
||||
dbe.printStackTrace();
|
||||
} catch (Exception e) {
|
||||
System.out.println("Exception: " + e.toString());
|
||||
e.printStackTrace();
|
||||
}
|
||||
System.out.println("All done.");
|
||||
}
|
||||
|
||||
} </pre>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="simpleda.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="persist_access.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="simpleget.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">SimpleDA.class </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Retrieving Objects from an Entity Store</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
318
docs/GettingStartedGuide/timetolive.html
Normal file
318
docs/GettingStartedGuide/timetolive.html
Normal file
|
|
@ -0,0 +1,318 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Using Time to Live</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="DBEntry.html" title="Chapter 8. Database Records" />
|
||||
<link rel="prev" href="usingDbt.html" title="Reading and Writing Database Records" />
|
||||
<link rel="next" href="bindAPI.html" title="Using the BIND APIs" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Using Time to Live</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="usingDbt.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 8. Database Records</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="bindAPI.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="timetolive"></a>Using Time to Live</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="toc">
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="timetolive.html#ttl-specify">Specifying a TTL Value</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="timetolive.html#ttl-update">Updating a TTL Value</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="timetolive.html#ttl-remove">Deleting TTL Expiration</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</div>
|
||||
<span>
|
||||
<p>
|
||||
Time to Live (TTL) is a mechanism that allows you to automatically
|
||||
expire
|
||||
|
||||
<span>database records.</span>
|
||||
TTL is expressed as the amount of time data is allowed to live in
|
||||
the
|
||||
|
||||
<span>database.</span>
|
||||
Data which has reached its expiration timeout value can no longer
|
||||
be retrieved, and will not appear in any
|
||||
|
||||
<span>database</span>
|
||||
statistics. Whether the data is physically removed from the
|
||||
|
||||
<span>database</span>
|
||||
is determined by an internal mechanism that is not
|
||||
user-controllable.
|
||||
</p>
|
||||
<p>
|
||||
TTL represents a minimum guaranteed time to live. Data expires on
|
||||
hour or day boundaries. This means that with a one hour TTL, there
|
||||
can be as much as two hours worth of unexpired data. For example
|
||||
(using a time format of hour:minute:second), given a one hour TTL,
|
||||
data written between 00:00:00.000 and 00:59:59.999 will expire at
|
||||
02:00:00.000 because the data is guaranteed to expire no less than
|
||||
one hour from when it is written.
|
||||
</p>
|
||||
<p>
|
||||
Expired data is invisible to queries and
|
||||
|
||||
<span>database</span>
|
||||
statistics, but even so it is using disk space until it has been
|
||||
purged. The expired data is purged from disk at some point in
|
||||
time after its expiration date. The exact time when the data is
|
||||
purged is driven by internal mechanisms and the workload on your
|
||||
|
||||
<span>database.</span>
|
||||
</p>
|
||||
<p>
|
||||
The TTL value for a
|
||||
|
||||
<span>database record</span>
|
||||
can be updated at any time before the expiration value has been
|
||||
reached. Data that has expired can no longer be modified, and this
|
||||
includes its TTL value.
|
||||
</p>
|
||||
<p>
|
||||
TTL is more efficient than manual user-deletion of the
|
||||
|
||||
<span>record</span>
|
||||
because it avoids the overhead of writing a database log entry for
|
||||
the data deletion. The deletion also does not appear in the
|
||||
replication stream.
|
||||
</p>
|
||||
<p>
|
||||
The following provides a brief introduction to using Time to Live.
|
||||
For a more complete description of this mechanism, see the
|
||||
<a class="ulink" href="../java/com/sleepycat/je/WriteOptions.html" target="_top">
|
||||
com.sleepycat.je.WriteOptions javadoc.
|
||||
</a>
|
||||
</p>
|
||||
</span>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="ttl-specify"></a>Specifying a TTL Value</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
TTL values are specified on a record by record basis using
|
||||
the <code class="classname">WriteOptions</code> class, which can
|
||||
but used by various <code class="methodname">put()</code> methods
|
||||
when writing to the database. For example, variations of
|
||||
<code class="methodname">Database.put()</code>,
|
||||
<code class="methodname">PrimaryIndex.put()</code>, and
|
||||
<code class="methodname">Cursor.put()</code> exist that accept a
|
||||
<code class="classname">WriteOptions</code> class instance.
|
||||
</p>
|
||||
<p>
|
||||
<code class="classname">WriteOptions</code> allows
|
||||
you to identify the number of days or hours the record will exist
|
||||
in the database before expiring. A duration interval specified in
|
||||
days is recommended because this results in the least amount of
|
||||
storage consumed in the store. However, if you want a TTL value
|
||||
that is not an even multiple of days, then specify the TTL
|
||||
value in hours.
|
||||
</p>
|
||||
<p>
|
||||
The code example from
|
||||
<a class="xref" href="usingDbt.html#databaseWrite" title="Writing Records to the Database">Writing Records to the Database</a>
|
||||
can be extended to specify a TTL value of 5 days like this:
|
||||
</p>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.je.Database;
|
||||
import com.sleepycat.je.DatabaseEntry;
|
||||
<strong class="userinput"><code>import com.sleepycat.je.Put;
|
||||
import com.sleepycat.je.WriteOptions;</code></strong>
|
||||
|
||||
|
||||
...
|
||||
|
||||
// Environment and database opens omitted for clarity.
|
||||
// Environment and database must NOT be opened read-only.
|
||||
|
||||
String aKey = "myFirstKey";
|
||||
String aData = "myFirstData";
|
||||
|
||||
try {
|
||||
DatabaseEntry theKey = new DatabaseEntry(aKey.getBytes("UTF-8"));
|
||||
DatabaseEntry theData = new DatabaseEntry(aData.getBytes("UTF-8"));
|
||||
|
||||
<strong class="userinput"><code>WriteOptions wo = new WriteOptions();
|
||||
// This sets the TTL using day units. Another variation
|
||||
// of setTTL() exists that accepts a TimeUnit class instance.
|
||||
wo.setTTL(5);
|
||||
myDatabase.put(null, // Transaction handle.
|
||||
theKey, // Record's key.
|
||||
theData, // Record's data.
|
||||
Put.NO_OVERWRITE, // If the record exists,
|
||||
// do not overwrite it.
|
||||
wo); // WriteOptions instance.</code></strong>
|
||||
|
||||
} catch (Exception e) {
|
||||
// Exception handling goes here
|
||||
} </pre>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="ttl-update"></a>Updating a TTL Value</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
To update the expiration time for a record, you update the
|
||||
record as normal, and at the same time specify the new expiration
|
||||
time. However, you must also indicate that the expiration time
|
||||
is to be updated. By default, you can modify the record and
|
||||
the expiration time will not be modified, even if you specify a
|
||||
new TTL value for the record.
|
||||
</p>
|
||||
<p>
|
||||
To indicate that the the expiration time is to be updated,
|
||||
specify <code class="literal">true</code> to the
|
||||
<code class="methodname">WriteOptions.setUpdateTTL()</code>
|
||||
method. For example, using the previous example, to change
|
||||
the TTL value to 10 days, do the following:
|
||||
</p>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.je.Database;
|
||||
import com.sleepycat.je.DatabaseEntry;
|
||||
import com.sleepycat.je.Put;
|
||||
import com.sleepycat.je.WriteOptions;
|
||||
|
||||
|
||||
...
|
||||
|
||||
// Environment and database opens omitted for clarity.
|
||||
// Environment and database must NOT be opened read-only.
|
||||
|
||||
String aKey = "myFirstKey";
|
||||
String aData = "myFirstData";
|
||||
|
||||
try {
|
||||
DatabaseEntry theKey = new DatabaseEntry(aKey.getBytes("UTF-8"));
|
||||
DatabaseEntry theData = new DatabaseEntry(aData.getBytes("UTF-8"));
|
||||
|
||||
WriteOptions wo = new WriteOptions();
|
||||
// This sets the TTL using day units. Another variation
|
||||
// of setTTL() exists that accepts a TimeUnit class instance.
|
||||
wo.setTTL(5);
|
||||
<strong class="userinput"><code>// If the record currently exists, update the TTL value
|
||||
wo.setUpdateTTL(true);</code></strong>
|
||||
myDatabase.put(null, // Transaction handle.
|
||||
theKey, // Record's key.
|
||||
theData, // Record's data.
|
||||
<strong class="userinput"><code>Put.OVERWRITE, // If the record exists,
|
||||
// overwrite it.</code></strong>
|
||||
wo); // WriteOptions instance.
|
||||
|
||||
} catch (Exception e) {
|
||||
// Exception handling goes here
|
||||
} </pre>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="ttl-remove"></a>Deleting TTL Expiration</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
If you have set a TTL value for a record and you later decide you
|
||||
do not want it to ever automatically expire, you can turn off
|
||||
TTL by setting a TTL value of <code class="literal">0</code>:
|
||||
</p>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.je.Database;
|
||||
import com.sleepycat.je.DatabaseEntry;
|
||||
import com.sleepycat.je.Put;
|
||||
import com.sleepycat.je.WriteOptions;
|
||||
|
||||
|
||||
...
|
||||
|
||||
// Environment and database opens omitted for clarity.
|
||||
// Environment and database must NOT be opened read-only.
|
||||
|
||||
String aKey = "myFirstKey";
|
||||
String aData = "myFirstData";
|
||||
|
||||
try {
|
||||
DatabaseEntry theKey = new DatabaseEntry(aKey.getBytes("UTF-8"));
|
||||
DatabaseEntry theData = new DatabaseEntry(aData.getBytes("UTF-8"));
|
||||
|
||||
WriteOptions wo = new WriteOptions();
|
||||
<strong class="userinput"><code>// Turn off automatic expiration of this record.
|
||||
wo.setTTL(0);</code></strong>
|
||||
wo.setUpdateTTL(true);
|
||||
myDatabase.put(null, // Transaction handle.
|
||||
theKey, // Record's key.
|
||||
theData, // Record's data.
|
||||
Put.OVERWRITE, // If the record exists,
|
||||
// overwrite it.
|
||||
wo); // WriteOptions instance.
|
||||
|
||||
} catch (Exception e) {
|
||||
// Exception handling goes here
|
||||
} </pre>
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="usingDbt.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="DBEntry.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="bindAPI.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Reading and Writing Database Records </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Using the BIND APIs</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
424
docs/GettingStartedGuide/usingDbt.html
Normal file
424
docs/GettingStartedGuide/usingDbt.html
Normal file
|
|
@ -0,0 +1,424 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Reading and Writing Database Records</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||||
<link rel="up" href="DBEntry.html" title="Chapter 8. Database Records" />
|
||||
<link rel="prev" href="DBEntry.html" title="Chapter 8. Database Records" />
|
||||
<link rel="next" href="timetolive.html" title="Using Time to Live" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Reading and Writing Database Records</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="DBEntry.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 8. Database Records</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="timetolive.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="usingDbt"></a>Reading and Writing Database Records</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="toc">
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="usingDbt.html#databaseWrite">Writing Records to the Database</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="usingDbt.html#databaseRead">Getting Records from the Database</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="usingDbt.html#recordDelete">Deleting Records</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="usingDbt.html#datapersist">Data Persistence</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</div>
|
||||
<p>
|
||||
When reading and writing database records, be aware that there are some
|
||||
slight differences in behavior depending on whether your database supports duplicate
|
||||
records. Two or more database records are considered to be duplicates of
|
||||
one another if they share the same key. The collection of records
|
||||
sharing the same key are called a <span class="emphasis"><em>duplicates set.</em></span>
|
||||
|
||||
|
||||
</p>
|
||||
<p>
|
||||
By default, JE databases do
|
||||
not support duplicate records. Where duplicate records are supported,
|
||||
cursors (see below) are used
|
||||
to access all of the records in the duplicates set.
|
||||
</p>
|
||||
<p>
|
||||
JE provides two basic mechanisms for the storage and retrieval of database
|
||||
key/data pairs:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
The
|
||||
<code class="methodname">Database.put()</code>
|
||||
|
||||
|
||||
and
|
||||
<code class="methodname">Database.get()</code>
|
||||
|
||||
|
||||
methods provide the easiest access for all non-duplicate records in the database.
|
||||
These methods are described in this section.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>Cursors provide several methods for putting and getting database
|
||||
records. Cursors and their database access methods are described in
|
||||
<a class="xref" href="Cursors.html" title="Chapter 9. Using Cursors">Using Cursors</a>.</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="databaseWrite"></a>Writing Records to the Database</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
Database records are stored in the internal BTree based on
|
||||
whatever sorting routine is available to the database. Records are
|
||||
sorted first by their key. If the database supports duplicate records,
|
||||
then the records for a specific key are sorted by their data.
|
||||
</p>
|
||||
<p>
|
||||
By default, JE sorts both keys and the data portion of duplicate
|
||||
records using unsigned byte-by-byte
|
||||
lexicographic comparisons. This default comparison works well for the
|
||||
majority of cases. However, in some case performance benefits can be
|
||||
realized by overriding the default comparison routine. See <a class="xref" href="comparator.html" title="Using Comparators">Using Comparators</a> for more information.
|
||||
</p>
|
||||
<p>You can use the following methods to put database records:</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
<code class="methodname">Database.put()</code>
|
||||
</p>
|
||||
<p>
|
||||
Puts a database record into the database. If your database does not
|
||||
support duplicate records, and if the provided key already exists in
|
||||
the database, then the currently existing record is replaced with
|
||||
the new data.
|
||||
</p>
|
||||
<p>
|
||||
Be aware that version of this method exists which accepts a
|
||||
<code class="classname">Put</code> enum. If <code class="literal">Put.OVERWRITE</code>
|
||||
is provided, then existing database records are
|
||||
overwritten. If <code class="literal">Put.NO_OVERWRITE</code> is
|
||||
provided, then existing records will not be overwritten.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="methodname">Database.putNoOverwrite()</code>
|
||||
</p>
|
||||
<p>
|
||||
Disallows overwriting (replacing) an existing record in the
|
||||
database. If the provided key already exists in the database,
|
||||
then this method returns
|
||||
<code class="literal">OperationStatus.KEYEXIST</code> even if
|
||||
the database supports duplicates.
|
||||
</p>
|
||||
<span>
|
||||
|
||||
</span>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="methodname">Database.putNoDupData()</code>
|
||||
</p>
|
||||
<p>
|
||||
Puts a database record into the database. If the provided key
|
||||
and data already exists in the database (that is, if you are
|
||||
attempting to put a record that compares equally to an existing
|
||||
record), then this returns
|
||||
<code class="literal">OperationStatus.KEYEXIST</code>.
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<p>
|
||||
When you put database records, you provide both the key and the data as
|
||||
<code class="classname">DatabaseEntry</code> objects. This means you must
|
||||
convert your key and data into a Java <code class="literal">byte</code> array. For
|
||||
example:
|
||||
</p>
|
||||
<a id="je_dbt3"></a>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.je.Database;
|
||||
import com.sleepycat.je.DatabaseEntry;
|
||||
|
||||
...
|
||||
|
||||
// Environment and database opens omitted for clarity.
|
||||
// Environment and database must NOT be opened read-only.
|
||||
|
||||
String aKey = "myFirstKey";
|
||||
String aData = "myFirstData";
|
||||
|
||||
try {
|
||||
DatabaseEntry theKey = new DatabaseEntry(aKey.getBytes("UTF-8"));
|
||||
DatabaseEntry theData = new DatabaseEntry(aData.getBytes("UTF-8"));
|
||||
myDatabase.put(null, theKey, theData);
|
||||
} catch (Exception e) {
|
||||
// Exception handling goes here
|
||||
} </pre>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="databaseRead"></a>Getting Records from the Database</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
The <code class="classname">Database</code> class provides several
|
||||
methods that you can use to retrieve database records. Note that if your
|
||||
database supports duplicate records, then these methods will only ever
|
||||
return the first record in a duplicate set. For this reason, if your
|
||||
database supports duplicates, you should use a cursor to retrieve
|
||||
records from it. Cursors are described in <a class="xref" href="Cursors.html" title="Chapter 9. Using Cursors">Using Cursors</a>.
|
||||
</p>
|
||||
<p>
|
||||
You can use either of the following methods to retrieve records from the database:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
<code class="methodname">Database.get()</code>
|
||||
</p>
|
||||
<p>Retrieves the record whose key matches the key provided to the
|
||||
method. If no records exists that uses the provided key, then
|
||||
<code class="literal">OperationStatus.NOTFOUND</code> is returned.</p>
|
||||
<span>
|
||||
|
||||
</span>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="methodname">Database.getSearchBoth()</code>
|
||||
</p>
|
||||
<p>Retrieve the record whose key matches both the key and the data
|
||||
provided to the method. If no record exists that uses the provided
|
||||
key and data, then <code class="literal">OperationStatus.NOTFOUND</code> is
|
||||
returned.</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<p>Both the key and data for a database record are returned as
|
||||
byte arrays in <code class="classname">DatabaseEntry</code> objects. These objects are
|
||||
passed as parameter values to the <code class="methodname">Database.get()</code> method.
|
||||
</p>
|
||||
<p>In order to retrieve your data once <code class="classname">Database.get()</code>
|
||||
has completed, you must retrieve the <code class="literal">byte</code> array stored
|
||||
in the <code class="classname">DatabaseEntry</code> and then convert that
|
||||
<code class="literal">byte</code> array back to the
|
||||
appropriate datatype. For example:</p>
|
||||
<a id="je_dbt4"></a>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.je.Database;
|
||||
import com.sleepycat.je.DatabaseEntry;
|
||||
import com.sleepycat.je.LockMode;
|
||||
import com.sleepycat.je.OperationStatus;
|
||||
|
||||
...
|
||||
|
||||
// Environment and database opens omitted for clarity.
|
||||
// Environment and database may be opened read-only.
|
||||
|
||||
String aKey = "myFirstKey";
|
||||
|
||||
try {
|
||||
// Create a pair of DatabaseEntry objects. theKey
|
||||
// is used to perform the search. theData is used
|
||||
// to store the data returned by the get() operation.
|
||||
DatabaseEntry theKey = new DatabaseEntry(aKey.getBytes("UTF-8"));
|
||||
DatabaseEntry theData = new DatabaseEntry();
|
||||
|
||||
// Perform the get.
|
||||
if (myDatabase.get(null, theKey, theData, LockMode.DEFAULT) ==
|
||||
OperationStatus.SUCCESS) {
|
||||
|
||||
// Recreate the data String.
|
||||
byte[] retData = theData.getData();
|
||||
String foundData = new String(retData, "UTF-8");
|
||||
System.out.println("For key: '" + aKey + "' found data: '" +
|
||||
foundData + "'.");
|
||||
} else {
|
||||
System.out.println("No record found for key '" + aKey + "'.");
|
||||
}
|
||||
} catch (Exception e) {
|
||||
// Exception handling goes here
|
||||
}</pre>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="recordDelete"></a>Deleting Records</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
|
||||
You can use the
|
||||
<code class="methodname">Database.delete()</code>
|
||||
|
||||
|
||||
method to delete a record from the database. If your database supports
|
||||
duplicate records, then all records associated with the provided key are
|
||||
deleted. To delete just one record from a list of duplicates, use a
|
||||
cursor. Cursors are described in <a class="xref" href="Cursors.html" title="Chapter 9. Using Cursors">Using Cursors</a>.
|
||||
|
||||
</p>
|
||||
<p>
|
||||
You can also delete every record in the database by using
|
||||
<code class="methodname">Environment.truncateDatabase().</code>
|
||||
|
||||
|
||||
</p>
|
||||
<p>For example:</p>
|
||||
<a id="je_dbt5"></a>
|
||||
<pre class="programlisting">package je.gettingStarted;
|
||||
|
||||
import com.sleepycat.je.Database;
|
||||
import com.sleepycat.je.DatabaseEntry;
|
||||
|
||||
...
|
||||
|
||||
// Environment and database opens omitted for clarity.
|
||||
// Environment and database can NOT be opened read-only.
|
||||
|
||||
try {
|
||||
String aKey = "myFirstKey";
|
||||
DatabaseEntry theKey = new DatabaseEntry(aKey.getBytes("UTF-8"));
|
||||
|
||||
// Perform the deletion. All records that use this key are
|
||||
// deleted.
|
||||
myDatabase.delete(null, theKey);
|
||||
} catch (Exception e) {
|
||||
// Exception handling goes here
|
||||
}</pre>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="datapersist"></a>Data Persistence</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
When you perform a database modification, your modification is made
|
||||
in the in-memory cache. This means that your data modifications
|
||||
are not necessarily flushed to disk, and so your data may not appear
|
||||
in the database after an application restart.
|
||||
</p>
|
||||
<p>
|
||||
Therefore, if you care if your data is durable across system
|
||||
failures, and to guard against the rare possibility of
|
||||
database corruption, you should use transactions to protect your
|
||||
database modifications. Every time you commit a transaction, JE
|
||||
ensures that the data will not be lost due to application or
|
||||
system failure. Transaction usage is described in the
|
||||
<span>
|
||||
<em class="citetitle">Berkeley DB, Java Edition Getting Started with Transaction Processing</em> guide.
|
||||
</span>
|
||||
|
||||
|
||||
|
||||
|
||||
</p>
|
||||
<p>
|
||||
If you do not want to use transactions, then the assumption is that
|
||||
your data is of a nature that it need not exist the next time your
|
||||
application starts. You may want this if, for example, you are using
|
||||
JE to cache data relevant only to the current application
|
||||
runtime.
|
||||
</p>
|
||||
<p>
|
||||
If, however, you are not using transactions for some reason and you
|
||||
still want some guarantee that your database modifications are
|
||||
persistent, then you should periodically
|
||||
<span>run environment syncs.</span>
|
||||
|
||||
|
||||
Syncs cause any dirty entries in the in-memory cache and the
|
||||
operating system's file cache to be written to disk. As
|
||||
such, they are quite expensive and you should use them sparingly.
|
||||
</p>
|
||||
<p>
|
||||
Note that by default, a sync is run every time you close an environment.
|
||||
You can also run a sync by calling the <code class="methodname">Environment.sync()</code>
|
||||
method.
|
||||
|
||||
|
||||
|
||||
</p>
|
||||
<p>
|
||||
For a brief description of how JE manages its data in the cache
|
||||
and in the log files, and how sync works, see <a class="xref" href="backuprestore.html#databaselogs" title="Databases and Log Files">Databases and Log Files</a>.
|
||||
</p>
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="DBEntry.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="DBEntry.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="timetolive.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Chapter 8. Database Records </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Using Time to Live</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
76
docs/LICENSE.txt
Normal file
76
docs/LICENSE.txt
Normal file
|
|
@ -0,0 +1,76 @@
|
|||
Copyright (C) 2002, 2016, Oracle and/or its affiliates. All rights reserved.
|
||||
|
||||
Licensed under the Apache License, Version 2.0 (the "License") reproduced below or available at:
|
||||
|
||||
http://www.apache.org/licenses/LICENSE-2.0
|
||||
|
||||
Unless required by applicable law or agreed to in writing, software
|
||||
distributed under the License is distributed on an "AS IS" BASIS,
|
||||
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
||||
See the License for the specific language governing permissions and
|
||||
limitations under the License.
|
||||
Apache License
|
||||
Version 2.0, January 2004
|
||||
http://www.apache.org/licenses/
|
||||
TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
|
||||
1. Definitions.
|
||||
"License" shall mean the terms and conditions for use, reproduction, and distribution as defined by Sections 1 through 9 of this document.
|
||||
"Licensor" shall mean the copyright owner or entity authorized by the copyright owner that is granting the License.
|
||||
"Legal Entity" shall mean the union of the acting entity and all other entities that control, are controlled by, or are under common control with that entity. For the purposes of this definition, "control" means (i) the power, direct or indirect, to cause the direction or management of such entity, whether by contract or otherwise, or (ii) ownership of fifty percent (50%) or more of the outstanding shares, or (iii) beneficial ownership of such entity.
|
||||
"You" (or "Your") shall mean an individual or Legal Entity exercising permissions granted by this License.
|
||||
"Source" form shall mean the preferred form for making modifications, including but not limited to software source code, documentation source, and configuration files.
|
||||
"Object" form shall mean any form resulting from mechanical transformation or translation of a Source form, including but not limited to compiled object code, generated documentation, and conversions to other media types.
|
||||
"Work" shall mean the work of authorship, whether in Source or Object form, made available under the License, as indicated by a copyright notice that is included in or attached to the work (an example is provided in the Appendix below).
|
||||
"Derivative Works" shall mean any work, whether in Source or Object form, that is based on (or derived from) the Work and for which the editorial revisions, annotations, elaborations, or other modifications represent, as a whole, an original work of authorship. For the purposes of this License, Derivative Works shall not include works that remain separable from, or merely link (or bind by name) to the interfaces of, the Work and Derivative Works thereof.
|
||||
"Contribution" shall mean any work of authorship, including the original version of the Work and any modifications or additions to that Work or Derivative Works thereof, that is intentionally submitted to Licensor for inclusion in the Work by the copyright owner or by an individual or Legal Entity authorized to submit on behalf of the copyright owner. For the purposes of this definition, "submitted" means any form of electronic, verbal, or written communication sent to the Licensor or its representatives, including but not limited to communication on electronic mailing lists, source code control systems, and issue tracking systems that are managed by, or on behalf of, the Licensor for the purpose of discussing and improving the Work, but excluding communication that is conspicuously marked or otherwise designated in writing by the copyright owner as "Not a Contribution."
|
||||
"Contributor" shall mean Licensor and any individual or Legal Entity on behalf of whom a Contribution has been received by Licensor and subsequently incorporated within the Work.
|
||||
2. Grant of Copyright License. Subject to the terms and conditions of this License, each Contributor hereby grants to You a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare Derivative Works of, publicly display, publicly perform, sublicense, and distribute the Work and such Derivative Works in Source or Object form.
|
||||
3. Grant of Patent License. Subject to the terms and conditions of this License, each Contributor hereby grants to You a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable (except as stated in this section) patent license to make, have made, use, offer to sell, sell, import, and otherwise transfer the Work, where such license applies only to those patent claims licensable by such Contributor that are necessarily infringed by their Contribution(s) alone or by combination of their Contribution(s) with the Work to which such Contribution(s) was submitted. If You institute patent litigation against any entity (including a cross-claim or counterclaim in a lawsuit) alleging that the Work or a Contribution incorporated within the Work constitutes direct or contributory patent infringement, then any patent licenses granted to You under this License for that Work shall terminate as of the date such litigation is filed.
|
||||
4. Redistribution. You may reproduce and distribute copies of the Work or Derivative Works thereof in any medium, with or without modifications, and in Source or Object form, provided that You meet the following conditions:
|
||||
1. You must give any other recipients of the Work or Derivative Works a copy of this License; and
|
||||
2. You must cause any modified files to carry prominent notices stating that You changed the files; and
|
||||
3. You must retain, in the Source form of any Derivative Works that You distribute, all copyright, patent, trademark, and attribution notices from the Source form of the Work, excluding those notices that do not pertain to any part of the Derivative Works; and
|
||||
4. If the Work includes a "NOTICE" text file as part of its distribution, then any Derivative Works that You distribute must include a readable copy of the attribution notices contained within such NOTICE file, excluding those notices that do not pertain to any part of the Derivative Works, in at least one of the following places: within a NOTICE text file distributed as part of the Derivative Works; within the Source form or documentation, if provided along with the Derivative Works; or, within a display generated by the Derivative Works, if and wherever such third-party notices normally appear. The contents of the NOTICE file are for informational purposes only and do not modify the License. You may add Your own attribution notices within Derivative Works that You distribute, alongside or as an addendum to the NOTICE text from the Work, provided that such additional attribution notices cannot be construed as modifying the License.
|
||||
|
||||
You may add Your own copyright statement to Your modifications and may provide additional or different license terms and conditions for use, reproduction, or distribution of Your modifications, or for any such Derivative Works as a whole, provided Your use, reproduction, and distribution of the Work otherwise complies with the conditions stated in this License.
|
||||
5. Submission of Contributions. Unless You explicitly state otherwise, any Contribution intentionally submitted for inclusion in the Work by You to the Licensor shall be under the terms and conditions of this License, without any additional terms or conditions. Notwithstanding the above, nothing herein shall supersede or modify the terms of any separate license agreement you may have executed with Licensor regarding such Contributions.
|
||||
6. Trademarks. This License does not grant permission to use the trade names, trademarks, service marks, or product names of the Licensor, except as required for reasonable and customary use in describing the origin of the Work and reproducing the content of the NOTICE file.
|
||||
7. Disclaimer of Warranty. Unless required by applicable law or agreed to in writing, Licensor provides the Work (and each Contributor provides its Contributions) on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied, including, without limitation, any warranties or conditions of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A PARTICULAR PURPOSE. You are solely responsible for determining the appropriateness of using or redistributing the Work and assume any risks associated with Your exercise of permissions under this License.
|
||||
8. Limitation of Liability. In no event and under no legal theory, whether in tort (including negligence), contract, or otherwise, unless required by applicable law (such as deliberate and grossly negligent acts) or agreed to in writing, shall any Contributor be liable to You for damages, including any direct, indirect, special, incidental, or consequential damages of any character arising as a result of this License or out of the use or inability to use the Work (including but not limited to damages for loss of goodwill, work stoppage, computer failure or malfunction, or any and all other commercial damages or losses), even if such Contributor has been advised of the possibility of such damages.
|
||||
9. Accepting Warranty or Additional Liability. While redistributing the Work or Derivative Works thereof, You may choose to offer, and charge a fee for, acceptance of support, warranty, indemnity, or other liability obligations and/or rights consistent with this License. However, in accepting such obligations, You may act only on Your own behalf and on Your sole responsibility, not on behalf of any other Contributor, and only if You agree to indemnify, defend, and hold each Contributor harmless for any liability incurred by, or claims asserted against, such Contributor by reason of your accepting any such warranty or additional liability.
|
||||
END OF TERMS AND CONDITIONS
|
||||
|
||||
|
||||
ADDITIONAL THIRD PARTY NOTICES:
|
||||
|
||||
|
||||
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
|
||||
/***
|
||||
* ASM: a very small and fast Java bytecode manipulation framework
|
||||
* Copyright (c) 2000-2005 INRIA, France Telecom
|
||||
* All rights reserved.
|
||||
*
|
||||
* Redistribution and use in source and binary forms, with or without
|
||||
* modification, are permitted provided that the following conditions
|
||||
* are met:
|
||||
* 1. Redistributions of source code must retain the above copyright
|
||||
* notice, this list of conditions and the following disclaimer.
|
||||
* 2. Redistributions in binary form must reproduce the above copyright
|
||||
* notice, this list of conditions and the following disclaimer in the
|
||||
* documentation and/or other materials provided with the distribution.
|
||||
* 3. Neither the name of the copyright holders nor the names of its
|
||||
* contributors may be used to endorse or promote products derived from
|
||||
* this software without specific prior written permission.
|
||||
*
|
||||
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
|
||||
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
||||
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
||||
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
|
||||
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
|
||||
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
|
||||
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
|
||||
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
|
||||
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
|
||||
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
|
||||
* THE POSSIBILITY OF SUCH DAMAGE.
|
||||
*/
|
||||
BIN
docs/ReplicationGuide/BerkeleyDB-JE-Replication.pdf
Normal file
BIN
docs/ReplicationGuide/BerkeleyDB-JE-Replication.pdf
Normal file
Binary file not shown.
147
docs/ReplicationGuide/addremovenodes.html
Normal file
147
docs/ReplicationGuide/addremovenodes.html
Normal file
|
|
@ -0,0 +1,147 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Adding and Removing Nodes</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB, Java Edition High Availability Applications" />
|
||||
<link rel="up" href="administration.html" title="Chapter 7. Administration" />
|
||||
<link rel="prev" href="backups.html" title="Running Backups" />
|
||||
<link rel="next" href="hotupgrade.html" title="Upgrading a JE Replication Group" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Adding and Removing Nodes</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="backups.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 7. Administration</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="hotupgrade.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="addremovenodes"></a>Adding and Removing Nodes</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
As described in <a class="xref" href="utilities.html#node-addremove" title="Adding and Removing Nodes from the Group">Adding and Removing Nodes from the Group</a>,
|
||||
a node is added to the replication group simply by starting it up
|
||||
and allowing it to perform its start-up handshake with the
|
||||
Master. Once an electable node has been added to the replication
|
||||
group, it belongs to the replication group forever, or until you
|
||||
explicitly remove it. Also, the node is uniquely identified within
|
||||
the replication group by a name that you must give it when you start
|
||||
up the process.
|
||||
</p>
|
||||
<p>
|
||||
This is worth remembering, because if you have electable nodes that
|
||||
have been added to the replication group, but which you then
|
||||
shutdown for a long period of time, your replication group might not
|
||||
be able to perform a lot of tasks, such as:
|
||||
</p>
|
||||
<div class="orderedlist">
|
||||
<ol type="1">
|
||||
<li>
|
||||
<p>
|
||||
Elect a Master.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Add a new node to the replicated group.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Delete a node from the replication group.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Successfully commit a transaction (this depends on the
|
||||
durability guarantees in place for your application).
|
||||
</p>
|
||||
</li>
|
||||
</ol>
|
||||
</div>
|
||||
<p>
|
||||
All of these actions might be adversely affected by a series of
|
||||
unavailable electable nodes because in order to do these things the
|
||||
Master must be in contact with a majority of the electable nodes
|
||||
belonging to the replication group (Monitor and Secondary nodes do
|
||||
not count). So if too many electable nodes are either shutdown or
|
||||
unavailable due to a network partition event, then these functions
|
||||
can become delayed or even completely unavailable.
|
||||
</p>
|
||||
<p>
|
||||
For this reason, if you have electable nodes that you want to
|
||||
shutdown for a long time, then you should remove those nodes from
|
||||
the replication group. JE provides a utility class that allows
|
||||
for node removal, so your application developer should have provided
|
||||
you with a tool of some kind that allows you to do this as a normal
|
||||
administrative function.
|
||||
</p>
|
||||
<p>
|
||||
When removing an electable node from the replication group, remember
|
||||
that:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
for best results, shut down the node first.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
a majority of the nodes must currently be in contact with
|
||||
the Master in order to acknowledge the node removal.
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<p>
|
||||
If at some later time you want to restart the node and have it
|
||||
join the replication group, you can do this using the normal
|
||||
procedure that your application uses when starting a node for
|
||||
the first time. Be aware, however, that you cannot reuse the
|
||||
unique name that the node was using when you removed it from
|
||||
the group as an electable node. Instead, give the node a
|
||||
completely new unique name before having it rejoin the
|
||||
replication group.
|
||||
</p>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="backups.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="administration.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="hotupgrade.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Running Backups </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Upgrading a JE Replication Group</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
229
docs/ReplicationGuide/administration.html
Normal file
229
docs/ReplicationGuide/administration.html
Normal file
|
|
@ -0,0 +1,229 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Chapter 7. Administration</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB, Java Edition High Availability Applications" />
|
||||
<link rel="up" href="index.html" title="Getting Started with Berkeley DB, Java Edition High Availability Applications" />
|
||||
<link rel="prev" href="repexample.html" title="Chapter 6. Replication Examples" />
|
||||
<link rel="next" href="admintimesync.html" title="Time Synchronization" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Chapter 7. Administration</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="repexample.html">Prev</a> </td>
|
||||
<th width="60%" align="center"> </th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="admintimesync.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="chapter" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title"><a id="administration"></a>Chapter 7. Administration</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="toc">
|
||||
<p>
|
||||
<b>Table of Contents</b>
|
||||
</p>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="administration.html#hardware">Hardware</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="admintimesync.html">Time Synchronization</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="nodeconfig.html">Node Configuration</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="backups.html">Running Backups</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="addremovenodes.html">Adding and Removing Nodes</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="hotupgrade.html">Upgrading a JE Replication Group</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dd>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="hotupgrade.html#idp1912848">Upgrade Process</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="hotupgrade.html#idp1949392">Things To Remember While Upgrading</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="hotupgrade.html#idp1959392">Handling Problems While Upgrading</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</dd>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="groupreset.html">Resetting a Replication Group</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</div>
|
||||
<p>
|
||||
This chapter describes issues pertaining to running a JE
|
||||
replication application. The topics discussed here have to do with
|
||||
hardware configuration, backups, node configuration, and other
|
||||
management issues that exist once the application has been
|
||||
placed into production.
|
||||
</p>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="hardware"></a>Hardware</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
A JE replicated application should run well on typical
|
||||
commodity multi-core hardware, although greater hardware
|
||||
requirements than this may be driven by the architecture of your
|
||||
particular application. Check with the software developers who
|
||||
wrote your JE replicated application for any additional
|
||||
requirements they may have over and above typical
|
||||
multi-core hardware.
|
||||
</p>
|
||||
<p>
|
||||
That said, keep the following in mind when putting a JE
|
||||
replication application into production:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
Examine the hardware you intend to use, and review it for
|
||||
common points of failure between nodes in the replication
|
||||
groups, such as shared power supplies, routers and so
|
||||
forth.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
The hardware that you use does not have to be identical
|
||||
across the entire production hardware. However, it is
|
||||
important to ensure that the least capable electable node
|
||||
has the resources to function as the Master.
|
||||
</p>
|
||||
<p>
|
||||
The Master is typically the node where demand for machine
|
||||
resources is the greatest. It needs to supply the
|
||||
replication streams for each active Replica, in addition
|
||||
to servicing the transaction load.
|
||||
</p>
|
||||
<p>
|
||||
Note that JE requires Monitor nodes to have minimal
|
||||
resource consumption (although, again, your application
|
||||
developers may have written your Monitor nodes such that
|
||||
they need resources over and above what JE requires),
|
||||
because Monitor nodes only listen for changes in the
|
||||
replication group.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Finally, your network is a critical part of your hardware
|
||||
requirements. It is critical that your network be capable
|
||||
of delivering adequate throughput under peak expected
|
||||
production work loads.
|
||||
</p>
|
||||
<p>
|
||||
Remember that your replicated application can consume
|
||||
quite a lot of network resources when a Replica starts up
|
||||
for the first time, or starts up after being shutdown for
|
||||
a long time. This is because the Replica must obtain all
|
||||
the data that it needs to operate. Essentially, this is a
|
||||
duplicate of the data contained by the Master node. So
|
||||
however much data the Master node holds, that much data
|
||||
will be transmitted across your network <span class="emphasis"><em>per
|
||||
node</em></span> every time you start a new node.
|
||||
</p>
|
||||
<p>
|
||||
For restarting nodes, the amount of data that will cross
|
||||
your network is equal to the delta between the time the
|
||||
Replica last shutdown and the state of your Master node
|
||||
at the time that the Replica is starting up again. If the
|
||||
Replica has been down for a long time (days or weeks),
|
||||
this can be quite a lot of data, depending on your Master
|
||||
node's workload.
|
||||
</p>
|
||||
<p>
|
||||
Be aware, however, that restarting nodes do not have to
|
||||
get their data from the Master node. It is possible for
|
||||
them to catch up, or nearly catch up, using data obtained
|
||||
from some other currently running Replica. See
|
||||
<a class="xref" href="logfile-restore.html" title="Restoring Log Files">Restoring Log Files</a>
|
||||
for more information.
|
||||
</p>
|
||||
<p>
|
||||
Good application performance also depends on the
|
||||
latency of network connections used by electable and
|
||||
monitor nodes to perform elections, report election
|
||||
results, and obtain acknowledgments. Consider
|
||||
deploying secondary nodes on machines with higher
|
||||
latency connections to the other members of the
|
||||
replication group, keeping in mind that these nodes
|
||||
still have the same throughput requirements as
|
||||
electable nodes.
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="repexample.html">Prev</a> </td>
|
||||
<td width="20%" align="center"> </td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="admintimesync.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Chapter 6. Replication Examples </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Time Synchronization</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
88
docs/ReplicationGuide/admintimesync.html
Normal file
88
docs/ReplicationGuide/admintimesync.html
Normal file
|
|
@ -0,0 +1,88 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Time Synchronization</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB, Java Edition High Availability Applications" />
|
||||
<link rel="up" href="administration.html" title="Chapter 7. Administration" />
|
||||
<link rel="prev" href="administration.html" title="Chapter 7. Administration" />
|
||||
<link rel="next" href="nodeconfig.html" title="Node Configuration" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Time Synchronization</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="administration.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 7. Administration</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="nodeconfig.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="admintimesync"></a>Time Synchronization</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
For best results, you are strongly recommended to synchronize the
|
||||
clocks on all the machines hosting your production
|
||||
replication group. Running a time synchronization daemon like
|
||||
<a class="ulink" href="http://www.ntp.org/" target="_top">NTPD</a> is a simple way to
|
||||
keep time synchronized across your replication machines. Once the
|
||||
clocks are set, they are maintained by ntpd so that they rarely
|
||||
stray more than 128ms away from one another.
|
||||
</p>
|
||||
<p>
|
||||
Be aware the JE checks for clock skew between the Master and
|
||||
a starting Replica node, when the Replica node performs its
|
||||
startup handshake with the Master. (See
|
||||
<a class="xref" href="lifecycle.html#lifecycle-nodestartup" title="Replica Startup">Replica Startup</a>
|
||||
for information on the startup handshake.) If the clock skew between
|
||||
the two nodes is too large, the handshake is aborted and JE
|
||||
throws an <a class="ulink" href="../java/com/sleepycat/je/EnvironmentFailureException.html" target="_top">EnvironmentFailureException</a>.
|
||||
</p>
|
||||
<p>
|
||||
Also, well-synchronized clocks are required for a proper
|
||||
implementation of a time consistency policy (see
|
||||
<a class="xref" href="consistency.html#timeconsistency" title="Time Consistency Policies">Time Consistency Policies</a>).
|
||||
It is also required for correct internal booking by JE.
|
||||
</p>
|
||||
<p>
|
||||
Finally, synchronized system clocks make it easier to correlate
|
||||
events in the logging output from different nodes in the group.
|
||||
</p>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="administration.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="administration.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="nodeconfig.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Chapter 7. Administration </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Node Configuration</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
220
docs/ReplicationGuide/availability.html
Normal file
220
docs/ReplicationGuide/availability.html
Normal file
|
|
@ -0,0 +1,220 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Availability</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB, Java Edition High Availability Applications" />
|
||||
<link rel="up" href="txn-management.html" title="Chapter 3. Transaction Management" />
|
||||
<link rel="prev" href="consistency.html" title="Managing Consistency" />
|
||||
<link rel="next" href="cons_and_dur.html" title="Consistency and Durability Use Cases" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Availability</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="consistency.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 3. Transaction Management</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="cons_and_dur.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="availability"></a>Availability</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="toc">
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="availability.html#writeavailability">Write Availability</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="availability.html#readavailability">Read Availability</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</div>
|
||||
<p>
|
||||
A key difference between standalone JE and JE HA is
|
||||
that for standalone JE the environment is available for
|
||||
both reads and writes as long as the application (including
|
||||
the underlying hardware) is functioning correctly. That is,
|
||||
the availability of a standalone JE application is
|
||||
independent of the local durability policy set for the
|
||||
transaction. However, the distributed nature of JE HA, means
|
||||
that availability can be dependent upon the state of other
|
||||
nodes in the replication group. It can also be dependent upon
|
||||
the policies you set for your HA application.
|
||||
</p>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="writeavailability"></a>Write Availability</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
JE HA requires that a simple majority of electable nodes be
|
||||
available to elect a Master. If a simple majority of those
|
||||
nodes is not available, the group is not available for
|
||||
writes because the group is unable to elect a Master.
|
||||
</p>
|
||||
<p>
|
||||
In the presence of a Master, the availability of a
|
||||
replicated environment (at the Master) for write
|
||||
operations is determined by the durability
|
||||
requirements associated with the transaction:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
If the transaction's durability requirements
|
||||
specify an acknowledgement policy of NONE, the
|
||||
Master is always available for write operations,
|
||||
just as is the case for standalone JE
|
||||
applications.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
If the durability requirements are made more
|
||||
stringent and specify a simple majority for
|
||||
acknowledgements, or if all
|
||||
the electable group members must acknowledge transaction
|
||||
commits, the environment might not be available for
|
||||
writes when one or more of the Electable Replicas is unable
|
||||
to provide an acknowledgment. This loss of write
|
||||
availability can occur even in the absence of
|
||||
hardware failures.
|
||||
</p>
|
||||
<p>
|
||||
Replicas might be unable to provide
|
||||
acknowledgements because a node is down. It could
|
||||
also occur if the Replica is simply lagging
|
||||
too far behind in the replication stream and so
|
||||
needs to commit earlier transactions before it can
|
||||
commit the current transaction. Note that in the
|
||||
absence of system level failures, the Replica will
|
||||
eventually commit the transaction, it just can not
|
||||
do so in the window of time required to indicate a
|
||||
successful commit of the transaction to the Master.
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<p>
|
||||
In other words, a durability policy that calls for commit
|
||||
acknowledgments can result in decreased availability of
|
||||
the system for write operations. It is important for
|
||||
you to keep this tradeoff in mind when choosing a
|
||||
durability policy.
|
||||
</p>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="readavailability"></a>Read Availability</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
A Master is always available for read operations because
|
||||
the data on it is always absolutely consistent. However,
|
||||
Replica read availability can be affected by the
|
||||
consistency policy that you are using:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
A Replica is always available for read operations
|
||||
that do not have any read consistency requirements.
|
||||
That is, when the Replica is allowed to lag
|
||||
arbitrarily far behind the Master, then the Replica
|
||||
will always be available to service read requests.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
If you are using higher levels of read consistency,
|
||||
then Replicas might not be available for read
|
||||
operations. This occurs when the Replica is forced
|
||||
to wait until it has caught up far enough in the
|
||||
replication stream before it can service a read
|
||||
operation. For example, if you choose a time
|
||||
consistency policy, and the the Replica cannot meet
|
||||
that consistency policy for a specific read
|
||||
operation, then the operation might be delayed or
|
||||
even abandoned entirely until the consistency
|
||||
policy can be met. This represents a loss of read
|
||||
availability.
|
||||
</p>
|
||||
<p>
|
||||
There are many reasons why a Replica might not be
|
||||
able to meet a consistency policy. For example,
|
||||
the Master might be very busy and so is unable to
|
||||
supply the Replica with the replication stream
|
||||
fast enough. Or, it could be because the Replica
|
||||
is experiencing very heavy read loads and so
|
||||
the replication stream might not be fast enough
|
||||
to keep up. It is also possible that the Replica
|
||||
has been down and is trying to catch up, which
|
||||
means that it might not be able to meet a
|
||||
consistency policy.
|
||||
</p>
|
||||
<p>
|
||||
All of these scenarios represent a loss of read
|
||||
availability, albeit a temporary one.
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<p>
|
||||
In other words, a consistency policy that requires the
|
||||
Replica to match the state of the Master to one degree or
|
||||
another can affect the Replica's read availability. It
|
||||
is important for you to keep this tradeoff in mind when
|
||||
choosing a consistency policy.
|
||||
</p>
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="consistency.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="txn-management.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="cons_and_dur.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Managing Consistency </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Consistency and Durability Use Cases</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
92
docs/ReplicationGuide/backups.html
Normal file
92
docs/ReplicationGuide/backups.html
Normal file
|
|
@ -0,0 +1,92 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Running Backups</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB, Java Edition High Availability Applications" />
|
||||
<link rel="up" href="administration.html" title="Chapter 7. Administration" />
|
||||
<link rel="prev" href="nodeconfig.html" title="Node Configuration" />
|
||||
<link rel="next" href="addremovenodes.html" title="Adding and Removing Nodes" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Running Backups</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="nodeconfig.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 7. Administration</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="addremovenodes.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="backups"></a>Running Backups</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
Because JE replication causes a current copy of your
|
||||
environment to be available at every data node in the group, the need
|
||||
for frequent backups is greatly reduced. Basically, every time a
|
||||
change is made on the Master, that change is backed up to every
|
||||
Replica node currently running. The result is that for each write
|
||||
operation you get a real-time incremental backup to
|
||||
<span class="emphasis"><em>n-1</em></span> nodes, where <span class="emphasis"><em>n</em></span> are
|
||||
the total number of data nodes (including the Master) currently
|
||||
running in your replication group.
|
||||
</p>
|
||||
<p>
|
||||
For this reason, JE does not currently support formal
|
||||
incremental backups of replicated environments. An application
|
||||
based upon the <a class="ulink" href="../java/com/sleepycat/je/util/DbBackup.html" target="_top">DbBackup</a> utility class can be written to allow
|
||||
administrators to create full backups. This is useful for
|
||||
creating a backup to be stored on offline media, if your data
|
||||
strategy calls for that level of protection.
|
||||
</p>
|
||||
<p>
|
||||
Remember that when performing a full backup, you should obtain
|
||||
the backup from a node that is current. Either use the Master
|
||||
node itself, or use a Replica node that must acknowledge a
|
||||
transaction commit before the commit operation can complete on
|
||||
the Master.
|
||||
</p>
|
||||
<p>
|
||||
Note that <a class="ulink" href="../java/com/sleepycat/je/util/DbBackup.html" target="_top">DbBackup</a> has some functionality that
|
||||
is specifically useful for replicated environments. See
|
||||
<a class="xref" href="dbbackup.html" title="Backing up a Replicated Application">Backing up a Replicated Application</a>
|
||||
for details.
|
||||
</p>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="nodeconfig.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="administration.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="addremovenodes.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Node Configuration </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Adding and Removing Nodes</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
390
docs/ReplicationGuide/cons_and_dur.html
Normal file
390
docs/ReplicationGuide/cons_and_dur.html
Normal file
|
|
@ -0,0 +1,390 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Consistency and Durability Use Cases</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB, Java Edition High Availability Applications" />
|
||||
<link rel="up" href="txn-management.html" title="Chapter 3. Transaction Management" />
|
||||
<link rel="prev" href="availability.html" title="Availability" />
|
||||
<link rel="next" href="txnrollback.html" title="Managing Transaction Rollbacks" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Consistency and Durability Use Cases</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="availability.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 3. Transaction Management</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="txnrollback.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="cons_and_dur"></a>Consistency and Durability Use Cases</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="toc">
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="cons_and_dur.html#outonthetown">Out on the Town</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="cons_and_dur.html#biolabs">Bio Labs, Inc</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</div>
|
||||
<p>
|
||||
As discussed throughout this chapter, there is an interaction
|
||||
between consistency and durability. This interaction results in
|
||||
design decisions that you will have to make when designing your
|
||||
HA application. To further illustrate this interaction, this
|
||||
section provides several use cases as examples of how
|
||||
durability and consistency policies are used to reach
|
||||
application design goals.
|
||||
</p>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="outonthetown"></a>Out on the Town</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
<span class="emphasis"><em>Out on the Town</em></span> is a social networking
|
||||
site about restaurants and artistic events. Restaurant
|
||||
locations and an event calendar are available on the site.
|
||||
Members can submit reviews about restaurants and events,
|
||||
and other members can comment on the reviews. Further,
|
||||
members maintain accounts and profiles.
|
||||
</p>
|
||||
<p>
|
||||
The site experiences most of its traffic as read-only
|
||||
requests. There is heavy read traffic from users who are
|
||||
browsing the site. In addition, periodic write traffic
|
||||
occurs as reviews and comments are submitted to the site.
|
||||
</p>
|
||||
<div class="sect3" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h4 class="title"><a id="oott-readreviews"></a>Reading Reviews</h4>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
Based on the site's usage characteristics, the web developers
|
||||
know that it is critical that the site perform well for read traffic.
|
||||
Listings must be readily available, and the site must be
|
||||
able to adapt to changing read loads. However, the site
|
||||
only needs a low threshold for most reads.
|
||||
</p>
|
||||
<p>
|
||||
While users should not experience a delay when they
|
||||
access the site, it is okay if read requests do not see
|
||||
the very latest reviews. For this reason, when starting
|
||||
read-only transactions for the purpose of viewing
|
||||
reviews, the application specifies a consistency policy
|
||||
of <a class="ulink" href="../java/com/sleepycat/je/rep/NoConsistencyRequiredPolicy.html" target="_top">NoConsistencyRequiredPolicy</a>. This provides the highest
|
||||
possible availability for read requests for the Replica
|
||||
nodes, which is the critical thing for this particular
|
||||
site. (Any other consistency policy might cause the
|
||||
node to delay reads while waiting for the node to meet
|
||||
its consistency policy, which would represent an
|
||||
unacceptable loss of availability as it could cost the
|
||||
site lost readership.)
|
||||
</p>
|
||||
</div>
|
||||
<div class="sect3" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h4 class="title"><a id="oott-writereviews"></a>Writing Reviews</h4>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
Most write operations are for new user reviews, and for comments on those
|
||||
reviews. For these writes, the application needs only a very lenient durability
|
||||
policy. It is not critical that a new review is immediately
|
||||
available to other users, nor is it critical that they are saved in the event of
|
||||
a catastrophic failure.
|
||||
</p>
|
||||
<p>
|
||||
Therefore, the application uses the convenience
|
||||
constant <a class="ulink" href="../java/com/sleepycat/je/Durability.html#COMMIT_WRITE_NO_SYNC" target="_top">Durability.COMMIT_WRITE_NO_SYNC</a> as the system default durability
|
||||
policy. (This is done by specifying the durability policy using
|
||||
<a class="ulink" href="../java/com/sleepycat/je/EnvironmentMutableConfig.html#setDurability(com.sleepycat.je.Durability)" target="_top">EnvironmentMutableConfig.setDurability()</a>.) This means:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
Write operations on the Master use
|
||||
<a class="ulink" href="../java/com/sleepycat/je/Durability.SyncPolicy.html#WRITE_NO_SYNC" target="_top">Durability.SyncPolicy.WRITE_NO_SYNC</a>.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
When the write operation is forwarded by the Master to the Replicas, those Replicas use
|
||||
<a class="ulink" href="../java/com/sleepycat/je/Durability.SyncPolicy.html#NO_SYNC" target="_top">Durability.SyncPolicy.NO_SYNC</a> when they internally update their own
|
||||
databases.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Only a simple majority of the Electable nodes need to acknowledge the
|
||||
update.
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
</div>
|
||||
<div class="sect3" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h4 class="title"><a id="oott-updateevents"></a>Updating Events and Restaurant Listings</h4>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
Periodically, the calendar of events and restaurant locations are updated. These
|
||||
write operations happen fairly infrequently relative to reviews and comments,
|
||||
but the site's operators deem this information to be of more importance (or
|
||||
valuable) than the reviews and comments. Therefore, they want a stronger
|
||||
guarantee that the information is backed up to all nodes, which is the same
|
||||
thing as saying they want a stronger durability guarantee. Nevertheless, they
|
||||
also want this class of writes to consume few resources.
|
||||
</p>
|
||||
<p>
|
||||
To achieve this, for transactions performing these kind of writes, the web
|
||||
engineers choose to override the site's default durability guarantee. Instead,
|
||||
they use a durability guarantee that:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
Uses <a class="ulink" href="../java/com/sleepycat/je/Durability.SyncPolicy.html#SYNC" target="_top">Durability.SyncPolicy.SYNC</a> for the local synchronization policy.
|
||||
This ensures that the write is fully backed up to the Master's local
|
||||
disk before the transaction commit operation returns.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Uses <a class="ulink" href="../java/com/sleepycat/je/Durability.SyncPolicy.html#WRITE_NO_SYNC" target="_top">Durability.SyncPolicy.WRITE_NO_SYNC</a> for the synchronization
|
||||
policy on the Replica nodes. This causes the updates to be written to
|
||||
the disk controller's buffers, but they are not flushed to disk before
|
||||
the Electable Replicas acknowledge the commit operation.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Stays with a simply majority for acknowledgements, which is the same as
|
||||
is used for the default durability policy.
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<p>
|
||||
That is, for updating events and restaurant locations, the application uses this
|
||||
durability policy:
|
||||
</p>
|
||||
<pre class="programlisting"> useForUpdates =
|
||||
new Durability(Durability.SyncPolicy.SYNC,
|
||||
Durability.SyncPolicy.WRITE_NO_SYNC,
|
||||
Durability.ReplicaAckPolicy.SIMPLE_MAJORITY); </pre>
|
||||
</div>
|
||||
<div class="sect3" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h4 class="title"><a id="oott-updateprofile"></a>Updating Account Profiles</h4>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
If a user makes an account profile change as part of a
|
||||
web session, she will naturally expect to see her
|
||||
changes when she next looks at the profile during the
|
||||
same session. From the user's perspective, this is all
|
||||
one operation: she causes her profile to change and
|
||||
then the profile page is refreshed with her new
|
||||
information.
|
||||
</p>
|
||||
<p>
|
||||
However, from the application's perspective, there are
|
||||
several things going on:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
A write transaction is performed on the Master.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
One or more read transactions are performed on the
|
||||
Replica node in use by the user as she updates
|
||||
her profile and then reads back the changes she
|
||||
just made.
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<p>
|
||||
To ensure that the session interaction looks
|
||||
intuitively consistent to the user, the application:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
Performs the write transaction on the Master.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Saves the <a class="ulink" href="../java/com/sleepycat/je/CommitToken.html" target="_top">CommitToken</a> for the account profile
|
||||
update within the web session.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
The Replica node uses a <a class="ulink" href="../java/com/sleepycat/je/rep/CommitPointConsistencyPolicy.html" target="_top">CommitPointConsistencyPolicy</a> policy for the
|
||||
follow-on account profile read(s). To do this, the application uses the
|
||||
<a class="ulink" href="../java/com/sleepycat/je/CommitToken.html" target="_top">CommitToken</a> stored in the previous step when beginning the read
|
||||
transactions. In this way, the Replica will not serve up the new profile
|
||||
page until it has received the profile updates from the Master. From the
|
||||
user's perspective, there may be a delay in her page refresh when she
|
||||
submits her updates. How long of a delay experienced by the user is a
|
||||
function of how busy the site is with write updates, as well as the
|
||||
performance characteristics of the hardware and networks in use by the
|
||||
site.
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="biolabs"></a>Bio Labs, Inc</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
<span class="emphasis"><em>Bio Labs, Inc</em></span> is a biotech company that is doing pharmaceutical
|
||||
production which must be audited by government agencies. Production sampling results
|
||||
are logged frequently. All such updates must be guaranteed to be backed up. (In
|
||||
other words, this application requires a very high durability guarantee.)
|
||||
</p>
|
||||
<p>
|
||||
In addition, there are frequent application defined sample points that represent
|
||||
phases in the production cycle. The application performs monitoring of the
|
||||
production stream. These reads are time critical, so the data must be no older
|
||||
than a specific point in time.
|
||||
</p>
|
||||
<div class="sect3" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h4 class="title"><a id="bli-logresults"></a>Logging Sampling Results</h4>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
Due to the auditing requirement for the sampling results, the application
|
||||
developers want an extremely high data durability guarantee. Therefore, they
|
||||
require the synchronization policy on both the
|
||||
Master and all Electable Replica nodes to
|
||||
be <a class="ulink" href="../java/com/sleepycat/je/Durability.SyncPolicy.html#SYNC" target="_top">Durability.SyncPolicy.SYNC</a>, which means that the logging data is guaranteed to
|
||||
be written to stable storage before the host returns from its transaction
|
||||
commit.
|
||||
</p>
|
||||
<p>
|
||||
For an acknowledgement policy, the engineers
|
||||
considered requiring all Electable nodes to
|
||||
acknowledge the commit. This would provide them with the strongest possible
|
||||
durability guarantee. However, they decided against this because it represents a
|
||||
possible loss of write availability for the
|
||||
application; if even one Electable node is
|
||||
shutdown or hidden by a network outage, then the Master would not be able to
|
||||
perform any write operations at all. So instead, the engineers stick with the
|
||||
default acknowledgement policy, which is to require a simple majority of the
|
||||
Electable nodes to acknowledge the commit.
|
||||
</p>
|
||||
<p>
|
||||
The durability policy, then, looks like this:
|
||||
</p>
|
||||
<pre class="programlisting"> resultsDurability =
|
||||
new Durability(Durability.SyncPolicy.SYNC,
|
||||
Durability.SyncPolicy.SYNC,
|
||||
Durability.ReplicaAckPolicy.SIMPLE_MAJORITY); </pre>
|
||||
</div>
|
||||
<div class="sect3" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h4 class="title"><a id="biolabs-monitor"></a>Monitoring the Production Stream</h4>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
The BioLabs application is required to monitor the production stream. All such
|
||||
monitoring must be of data that is no older than a defined age.
|
||||
</p>
|
||||
<p>
|
||||
This represents a read activity that has a time concurrency policy requirement.
|
||||
Therefore, whenever the application performs a write (that is, logs sampling
|
||||
results), the application creates a <a class="ulink" href="../java/com/sleepycat/je/CommitToken.html" target="_top">CommitToken</a>. Each of the nodes, then, use
|
||||
this commit token to specify a <a class="ulink" href="../java/com/sleepycat/je/rep/CommitPointConsistencyPolicy.html" target="_top">CommitPointConsistencyPolicy</a> policy when the
|
||||
<a class="ulink" href="../java/com/sleepycat/je/Environment.html#beginTransaction(com.sleepycat.je.Transaction, com.sleepycat.je.TransactionConfig)" target="_top">Environment.beginTransaction()</a> method is called. This guarantees that the
|
||||
application's data monitoring activities will be performed on data that is not
|
||||
out of date or stale.
|
||||
</p>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="availability.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="txn-management.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="txnrollback.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Availability </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Managing Transaction Rollbacks</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
508
docs/ReplicationGuide/consistency.html
Normal file
508
docs/ReplicationGuide/consistency.html
Normal file
|
|
@ -0,0 +1,508 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Managing Consistency</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB, Java Edition High Availability Applications" />
|
||||
<link rel="up" href="txn-management.html" title="Chapter 3. Transaction Management" />
|
||||
<link rel="prev" href="txn-management.html" title="Chapter 3. Transaction Management" />
|
||||
<link rel="next" href="availability.html" title="Availability" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Managing Consistency</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="txn-management.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 3. Transaction Management</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="availability.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="consistency"></a>Managing Consistency</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="toc">
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="consistency.html#setconsistencypolicy">Setting Consistency Policies</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="consistency.html#timeconsistency">Time Consistency Policies</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="consistency.html#commitpointconsistency">Commit Point Consistency Policies</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</div>
|
||||
<p>
|
||||
In a traditional stand-alone transactional application, <span class="emphasis"><em>consistency</em></span>
|
||||
means that a transaction takes the database from one consistent state to another. What
|
||||
defines a consistent state is application-specific. This transition is made atomically,
|
||||
that is, either all the operations that constitute the transaction are performed, or
|
||||
none of them are. JE HA supports this type of transactional consistency both on the
|
||||
Master, as well as on the Replicas as the replication stream is replayed. That is, in
|
||||
the absence of failures, the Replicas will see exactly the same sequence of transitions,
|
||||
from one consistent state to another, as the Master.
|
||||
|
||||
</p>
|
||||
<p>
|
||||
A JE HA application must additionally concern itself with the data consistency of
|
||||
the Replica with respect to the Master. In a distributed system like JE HA, the
|
||||
changes made at the Master are not always instantaneously available at every Replica,
|
||||
although they eventually will be. For example, consider a
|
||||
three node group, containing only Electable nodes, where a
|
||||
change is made on the Master and the transaction is committed with a durability policy
|
||||
requiring acknowledgments from a simple majority of nodes. After a successful commit of
|
||||
this transaction, the changes will be available at the Master and at one other Replica,
|
||||
thus satisfying the requirement for a simple majority of acknowledgments. The state of
|
||||
the Master and the acknowledging Replica will be consistent with each other after the
|
||||
transaction has been committed, but the transaction commit makes no guarantees about the
|
||||
state of the third Replica after the commit.
|
||||
</p>
|
||||
<p>
|
||||
In general, Replicas not directly involved in contributing to the acknowledgment of a
|
||||
transaction commit will lag in the replay of the replication stream because they do not
|
||||
synchronize their commits with the Master. As a consequence, their state, on an
|
||||
instantaneous basis, may not be current with respect to the Master. However, in the
|
||||
absence of further updates, all Replicas will eventually catch up and reflect the
|
||||
instantaneous state of the Master. This means that a Replica which is not
|
||||
consistent with the Master simply reflects an earlier locally consistent state at the
|
||||
Master because transaction updates on the Replica are always applied, atomically and in
|
||||
order. From the application's perspective, the environment on the Replica goes through
|
||||
exactly the same sequence of changes to its persistent state as the Master.
|
||||
</p>
|
||||
<p>
|
||||
A Replica may similarly lag behind the Master if it has been down for some period of
|
||||
time and was unable to communicate with the Master. Such a Replica will catch up, when
|
||||
it is brought back up and will eventually become consistent with the Master.
|
||||
</p>
|
||||
<p>
|
||||
Given the distributed nature of a JE HA application, and the fact that some nodes
|
||||
might lag behind the Master, the question you have to ask yourself is how long will it take for
|
||||
that node to be consistent relative to the Master. More to the
|
||||
point: how far behind the Master are you willing to allow the node to lag?
|
||||
</p>
|
||||
<p>
|
||||
This should be one of your biggest concerns when it comes to
|
||||
architecting a JE HA application.
|
||||
</p>
|
||||
<p>
|
||||
You define how current the nodes in your replication group must
|
||||
be by defining a <span class="emphasis"><em>consistency policy</em></span>.
|
||||
You define your consistency policy using an implementation of the
|
||||
<a class="ulink" href="../java/com/sleepycat/je/ReplicaConsistencyPolicy.html" target="_top">ReplicaConsistencyPolicy</a> interface. This interface allows you
|
||||
to define how current the Replica must be before a transaction
|
||||
can be started on the Replica. (Remember that all read
|
||||
operations are performed within a transaction.) If the Replica
|
||||
is not current enough, then the start of that transaction is
|
||||
delayed until that level of consistency has been reached. This
|
||||
means that Replicas that are not current enough will block read
|
||||
operations until they are brought up to date.
|
||||
</p>
|
||||
<p>
|
||||
Obviously your consistency policy can have an affect on your Replica's read performance
|
||||
by increasing the latency experienced by read transactions. This is because transactions
|
||||
may have to wait to either begin or commit until the consistency policy can be
|
||||
satisfied. If the consistency policy is so stringent that it cannot be satisfied using
|
||||
the available resources, the Replica's availability for reads may deteriorate as
|
||||
transactions timeout. A <a class="ulink" href="../java/com/sleepycat/je/Durability.SyncPolicy.html#SYNC" target="_top">Durability.SyncPolicy.SYNC</a> policy on the Replica can slow
|
||||
down write operations on the Replica, making it harder for the Replica to meet its
|
||||
consistency guarantee. Conversely, a <a class="ulink" href="../java/com/sleepycat/je/Durability.SyncPolicy.html#NO_SYNC" target="_top">Durability.SyncPolicy.NO_SYNC</a> policy on the
|
||||
Replica makes it easy for the Replica to keep up, which means you can have a stronger
|
||||
consistency guarantee.
|
||||
</p>
|
||||
<p>
|
||||
One of three interface implementations are available for you to
|
||||
use when defining your consistency policy:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
<a class="ulink" href="../java/com/sleepycat/je/rep/NoConsistencyRequiredPolicy.html" target="_top">NoConsistencyRequiredPolicy</a>
|
||||
</p>
|
||||
<p>
|
||||
No consistency policy is enforced. This policy allows
|
||||
a transaction on a Replica to proceed regardless of the
|
||||
state of the Replica relative to the Master. This
|
||||
policy can also be used to access a database when the
|
||||
replication node is in a DETACHED state.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<a class="ulink" href="../java/com/sleepycat/je/rep/TimeConsistencyPolicy.html" target="_top">TimeConsistencyPolicy</a>
|
||||
</p>
|
||||
<p>
|
||||
Defines how far back in time the Replica is permitted
|
||||
to lag the Master.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<a class="ulink" href="../java/com/sleepycat/je/rep/CommitPointConsistencyPolicy.html" target="_top">CommitPointConsistencyPolicy</a>
|
||||
</p>
|
||||
<p>
|
||||
Defines consistency in terms of a specified commit
|
||||
token. That is, the Replica must be at least as current
|
||||
as the <a class="ulink" href="../java/com/sleepycat/je/CommitToken.html" target="_top">CommitToken</a> provided to this class.
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="setconsistencypolicy"></a>Setting Consistency Policies</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
You set a consistency policy by using
|
||||
<a class="ulink" href="../java/com/sleepycat/je/rep/ReplicationConfig.html#setConsistencyPolicy(com.sleepycat.je.ReplicaConsistencyPolicy)" target="_top">ReplicationConfig.setConsistencyPolicy()</a>.
|
||||
For example:
|
||||
</p>
|
||||
<pre class="programlisting"> EnvironmentConfig envConfig = new EnvironmentConfig();
|
||||
envConfig.setAllowCreate(true);
|
||||
envConfig.setTransactional(true);
|
||||
|
||||
// Require no synchronization for transactional commit on the
|
||||
// Master, but full synchronization on the Replicas. Also,
|
||||
// wait for acknowledgements from a simple majority of Replicas.
|
||||
Durability durability =
|
||||
new Durability(Durability.SyncPolicy.NO_SYNC,
|
||||
Durability.SyncPolicy.SYNC,
|
||||
Durability.ReplicaAckPolicy.SIMPLE_MAJORITY);
|
||||
|
||||
envConfig.setDurability(durability);
|
||||
|
||||
// Identify the node
|
||||
ReplicationConfig repConfig =
|
||||
new ReplicationConfig("PlanetaryRepGroup",
|
||||
"Jupiter",
|
||||
"jupiter.example.com:5002");
|
||||
|
||||
// Use the node at mercury.example.com:5001 as a helper to find the rest
|
||||
// of the group.
|
||||
repConfig.setHelperHosts("mercury.example.com:5001");
|
||||
|
||||
<strong class="userinput"><code>// Turn off consistency policies. Transactions can occur
|
||||
// regardless of how consistent the Replica is relative
|
||||
// to the Master.
|
||||
NoConsistencyRequiredPolicy ncrp =
|
||||
new NoConsistencyRequiredPolicy();
|
||||
repConfig.setConsistencyPolicy(ncrp);</code></strong>
|
||||
|
||||
ReplicatedEnvironment repEnv =
|
||||
new ReplicatedEnvironment(home, repConfig, envConfig); </pre>
|
||||
<p>
|
||||
Note that the consistency policy is set on a node-by-node
|
||||
basis. There is no requirement that you set the same policy for
|
||||
every node in your replication group.
|
||||
</p>
|
||||
<p>
|
||||
You can also set consistency policies on a
|
||||
transaction-by-transaction basis when you begin the
|
||||
transaction:
|
||||
</p>
|
||||
<pre class="programlisting"> // Turn off consistency policies. The transactions can
|
||||
// be performed regardless of how consistent the Replica is
|
||||
// relative to the Master.
|
||||
NoConsistencyRequiredPolicy ncrp =
|
||||
new NoConsistencyRequiredPolicy();
|
||||
|
||||
TransactionConfig tc = new TransactionConfig();
|
||||
tc.setConsistencyPolicy(ncrp);
|
||||
// env is a ReplicatedEnvironment handle
|
||||
env.beginTransaction(null, tc); </pre>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="timeconsistency"></a>Time Consistency Policies</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
A time consistency policy is a time-oriented policy that
|
||||
defines how far back in time the Replica is permitted to
|
||||
lag the Master. It does so by comparing the time
|
||||
associated with the latest transaction committed on the
|
||||
Master with the current time. If the Replica lags by an
|
||||
amount greater than the permissible lag, it will hold back
|
||||
the start of the transaction until the Replica has replayed
|
||||
enough of the replication stream to narrow the lag to
|
||||
within the permissible lag.
|
||||
</p>
|
||||
<p>
|
||||
Use of a time based consistency policy requires that nodes
|
||||
in a replication group have their clocks reasonably
|
||||
synchronized. This can be easily achieved using a daemon
|
||||
like <a class="ulink" href="http://www.ntp.org/" target="_top">NTPD</a>.
|
||||
</p>
|
||||
<p>
|
||||
You implement a time-based consistency policy by using the
|
||||
<a class="ulink" href="../java/com/sleepycat/je/rep/TimeConsistencyPolicy.html" target="_top">TimeConsistencyPolicy</a> class. To instantiate this class,
|
||||
you provide it with the following:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
A number representing the permissible lag.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
A <a class="ulink" href="http://java.sun.com/j2se/1.5/docs/api/java/util/concurrent/TimeUnit.html" target="_top">TimeUnit</a> constant indicating the units of time
|
||||
that the permissible lag represents.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
A number representing the timeout period during
|
||||
which a transaction will wait for the Replica to
|
||||
catch up so that the consistency policy can be met.
|
||||
If the transaction waits more than the timeout
|
||||
period, a <a class="ulink" href="../java/com/sleepycat/je/rep/ReplicaConsistencyException.html" target="_top">ReplicaConsistencyException</a> is thrown.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
A <a class="ulink" href="http://java.sun.com/j2se/1.5/docs/api/java/util/concurrent/TimeUnit.html" target="_top">TimeUnit</a> constant indicating the units of time
|
||||
in use for the timeout value.
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<p>
|
||||
For example:
|
||||
</p>
|
||||
<pre class="programlisting"> EnvironmentConfig envConfig = new EnvironmentConfig();
|
||||
envConfig.setAllowCreate(true);
|
||||
envConfig.setTransactional(true);
|
||||
|
||||
// Require no synchronization for transactional commit on the
|
||||
// Master, but full synchronization on the Replicas. Also,
|
||||
// wait for acknowledgements from a simple majority of Replicas.
|
||||
Durability durability =
|
||||
new Durability(Durability.SyncPolicy.NO_SYNC,
|
||||
Durability.SyncPolicy.SYNC,
|
||||
Durability.ReplicaAckPolicy.SIMPLE_MAJORITY);
|
||||
|
||||
envConfig.setDurability(durability);
|
||||
|
||||
// Identify the node
|
||||
ReplicationConfig repConfig =
|
||||
new ReplicationConfig("PlanetaryRepGroup",
|
||||
"Jupiter",
|
||||
"jupiter.example.com:5002");
|
||||
|
||||
// Use the node at mercury.example.com:5001 as a helper to find the rest
|
||||
// of the group.
|
||||
repConfig.setHelperHosts("mercury.example.com:5001");
|
||||
|
||||
<strong class="userinput"><code>// Set consistency policy for replica.
|
||||
TimeConsistencyPolicy consistencyPolicy = new TimeConsistencyPolicy
|
||||
(1, TimeUnit.SECONDS, /* 1 sec of lag */
|
||||
10, TimeUnit.SECONDS /* Wait up to 10 sec */);
|
||||
repConfig.setConsistencyPolicy(consistencyPolicy);</code></strong>
|
||||
|
||||
ReplicatedEnvironment repEnv =
|
||||
new ReplicatedEnvironment(home, repConfig, envConfig); </pre>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="commitpointconsistency"></a>Commit Point Consistency Policies</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
A commit point consistency policy defines consistency in
|
||||
terms of the commit of a specific transaction. This policy
|
||||
can be used to ensure that a Replica is at least current
|
||||
enough to have the changes made by a specific transaction.
|
||||
Because transactions are applied serially, by ensuring a
|
||||
Replica has a specific commit applied to it, you know that
|
||||
all transaction commits occurring prior to the specified
|
||||
transaction have also been applied to the Replica.
|
||||
</p>
|
||||
<p>
|
||||
As is the case with a time consistency policy, if the
|
||||
Replica is not current enough relative to the Master, all
|
||||
attempts to begin a transaction will be delayed until the
|
||||
Replica has caught up. If the Replica does not catch up
|
||||
within a specified timeout period, the transaction will
|
||||
throw a <a class="ulink" href="../java/com/sleepycat/je/rep/ReplicaConsistencyException.html" target="_top">ReplicaConsistencyException</a>.
|
||||
</p>
|
||||
<p>
|
||||
In order to specify a commit point consistency policy, you
|
||||
must provide a <a class="ulink" href="../java/com/sleepycat/je/CommitToken.html" target="_top">CommitToken</a> that is used to identify the
|
||||
transaction that the Replica must have in order to be
|
||||
current enough. Because the commit point that you care
|
||||
about will change from transaction to transaction, you do
|
||||
not specify commit point consistency policies on an
|
||||
environment-wide basis. Instead, you specify them when you
|
||||
begin a transaction.
|
||||
</p>
|
||||
<p>
|
||||
For example, suppose the application is a web application
|
||||
where a replicated group is implemented within a load
|
||||
balanced web server group. Each request to the web server
|
||||
consists of an update operation followed by read operations
|
||||
(say from the same client), The read operations naturally
|
||||
expect to see the data from the updates executed by the
|
||||
same request. However, the read operations might have been
|
||||
routed to a node that did not execute the update.
|
||||
</p>
|
||||
<p>
|
||||
In such a case, the update request would generate a
|
||||
<a class="ulink" href="../java/com/sleepycat/je/CommitToken.html" target="_top">CommitToken</a>, which would be resubmitted by the browser,
|
||||
along with subsequent read requests. The read request could
|
||||
be directed at any one of the available web servers by a
|
||||
load balancer. The node which executes the read request
|
||||
would create a <a class="ulink" href="../java/com/sleepycat/je/rep/CommitPointConsistencyPolicy.html" target="_top">CommitPointConsistencyPolicy</a> with that
|
||||
<a class="ulink" href="../java/com/sleepycat/je/CommitToken.html" target="_top">CommitToken</a> and use it at transaction begin. If the
|
||||
environment at the web server was already current enough,
|
||||
it could immediately execute the transaction
|
||||
and satisfy the request. If not, the "transaction begin"
|
||||
would stall until the Replica replay had caught up and the
|
||||
change was available at that web server.
|
||||
</p>
|
||||
<p>
|
||||
You obtain a commit token using the
|
||||
<a class="ulink" href="../java/com/sleepycat/je/Transaction.html#getCommitToken()" target="_top">Transaction.getCommitToken()</a> method. Use this method after
|
||||
you have successfully committed the transaction that you
|
||||
want to base a <a class="ulink" href="../java/com/sleepycat/je/rep/CommitPointConsistencyPolicy.html" target="_top">CommitPointConsistencyPolicy</a> upon.
|
||||
</p>
|
||||
<p>
|
||||
For example:
|
||||
</p>
|
||||
<pre class="programlisting">Database myDatabase = null;
|
||||
Environment myEnv = null;
|
||||
CommitToken ct = null;
|
||||
try {
|
||||
...
|
||||
// Environment and database setup removed for brevity
|
||||
...
|
||||
|
||||
Transaction txn = myEnv.beginTransaction(null, null);
|
||||
|
||||
try {
|
||||
myDatabase.put(txn, key, data);
|
||||
txn.commit();
|
||||
ct = txn.getCommitToken();
|
||||
if (ct != null) {
|
||||
// Do something with the commit token to
|
||||
// forward it to the Replica where you
|
||||
// want to use it.
|
||||
}
|
||||
} catch (Exception e) {
|
||||
if (txn != null) {
|
||||
txn.abort();
|
||||
txn = null;
|
||||
}
|
||||
}
|
||||
|
||||
} catch (DatabaseException de) {
|
||||
// Exception handling goes here
|
||||
} </pre>
|
||||
<p>
|
||||
To create your commit point token consistency policy, transfer the
|
||||
commit token to the Replica performing a read using whatever
|
||||
mechanism that makes sense for your HA application, and then create
|
||||
the policy for that specific transaction handle:
|
||||
Note that <a class="ulink" href="../java/com/sleepycat/je/CommitToken.html" target="_top">CommitToken</a> implements <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/io/Serializable.html" target="_top">Serializable</a>, so you can
|
||||
use the standard Java serialization mechanisms when passing the
|
||||
commit token between processes.
|
||||
</p>
|
||||
<pre class="programlisting">Database myDatabase = null;
|
||||
Environment myEnv = null;
|
||||
CommitToken ct = null;
|
||||
try {
|
||||
...
|
||||
// Environment and database setup removed for brevity
|
||||
...
|
||||
|
||||
CommitPointConsistencyPolicy cpcp =
|
||||
new CommitPointConsistencyPolicy(ct, // The commit token
|
||||
10, TimeUnit.SECONDS); // Timeout value
|
||||
|
||||
TransactionConfig txnConfig = new TransactionConfig();
|
||||
txnConfig.setConsistencyPolicy(cpcp);
|
||||
|
||||
|
||||
Transaction txn = myEnv.beginTransaction(null, txnConfig);
|
||||
|
||||
try {
|
||||
// Perform your database read here using the transaction
|
||||
// handle, txn.
|
||||
txn.commit();
|
||||
} catch (Exception e) {
|
||||
// There are quite a lot of different exceptions that can be
|
||||
// seen at this level, including the LockConflictException.
|
||||
// We just catch Exception for this example for simplicity's
|
||||
// sake.
|
||||
if (txn != null) {
|
||||
txn.abort();
|
||||
txn = null;
|
||||
}
|
||||
}
|
||||
|
||||
} catch (ReplicaConsistencyException rce) {
|
||||
// Deal with this timeout error here. It is thrown by the
|
||||
// beginTransaction operation if the consistency policy
|
||||
// cannot be met within the timeout time.
|
||||
} catch (DatabaseException de) {
|
||||
// Database exception handling goes here.
|
||||
} catch (Exception ee) {
|
||||
// General exception handling goes here.
|
||||
}</pre>
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="txn-management.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="txn-management.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="availability.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Chapter 3. Transaction Management </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Availability</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
278
docs/ReplicationGuide/datamanagement.html
Normal file
278
docs/ReplicationGuide/datamanagement.html
Normal file
|
|
@ -0,0 +1,278 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Managing Data Guarantees</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB, Java Edition High Availability Applications" />
|
||||
<link rel="up" href="introduction.html" title="Chapter 1. Introduction" />
|
||||
<link rel="prev" href="introduction.html" title="Chapter 1. Introduction" />
|
||||
<link rel="next" href="lifecycle.html" title="Replication Group Life Cycle" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Managing Data Guarantees</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="introduction.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 1. Introduction</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="lifecycle.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="datamanagement"></a>Managing Data Guarantees</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="toc">
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="datamanagement.html#durability-intro">Durability</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="datamanagement.html#consistency-intro">Managing Data Consistency</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</div>
|
||||
<p>
|
||||
All replicated applications are first transactional
|
||||
applications. This means that you have the standard data
|
||||
guarantee issues to consider, all of which have to do with
|
||||
how durable and consistent you want your data to be. Of
|
||||
course, considerations of this nature also play a role in
|
||||
your application's performance. These issues are even more
|
||||
important for replicated applications because replication
|
||||
adds additional dimensions to them.
|
||||
</p>
|
||||
<p>
|
||||
Notably, in a replicated application you must decide how
|
||||
durable your data is, by deciding how careful the Master will
|
||||
be to make sure a data write has been written to disk on its
|
||||
various Replica nodes before completing the transaction.
|
||||
</p>
|
||||
<p>
|
||||
Consistency also adds an additional dimension in a replicated
|
||||
application, because now you must decide how consistent the
|
||||
various nodes in the replication group will be relative to
|
||||
the Master at any given time. If no writes are being
|
||||
performed on the Master, all Replicas will eventually catch
|
||||
up to the Master and so be completely consistent with it.
|
||||
But for most HA applications, writes are occurring on the
|
||||
Master, and so it is possible for some number of your
|
||||
Replicas to lag behind the Master. What you have to decide,
|
||||
then, is how sensitive your application is to this kind of
|
||||
temporary inconsistency.
|
||||
</p>
|
||||
<p>
|
||||
Note that your consistency requirements can be gated by your
|
||||
durability requirements. Durability, in turn, can be gated by
|
||||
any concerns you might have on write throughput. At the same
|
||||
time, your consistency requirement can have an affect on the
|
||||
read performance of your Replicas. It is
|
||||
therefore a mistake to think about any one of these
|
||||
requirements in the absence of the others.
|
||||
</p>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="durability-intro"></a>Durability</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
One of the reasons you might be writing a replicated
|
||||
application is to achieve a higher durability guarantee
|
||||
than you can get with a traditional transactional
|
||||
application. In a traditional application, your data's
|
||||
durability is a function of how you perform your
|
||||
transactional commits, and how frequently you perform
|
||||
your backups. For this class of application, the
|
||||
strongest durability guarantee you can have is to use
|
||||
synchronous commits (the commit does not
|
||||
complete until the data is written to disk), coupled with
|
||||
very frequent backups of your environment.
|
||||
</p>
|
||||
<p>
|
||||
The problem with a stand-alone application in which you
|
||||
are seeking a very high durability guarantee is that your
|
||||
write throughput will suffer. Synchronous commits
|
||||
require disk writes, and disk I/O is one of the most
|
||||
expensive operations you can ask a database to perform.
|
||||
</p>
|
||||
<p>
|
||||
In order to increase write throughput in your
|
||||
transactional application, you may decide to use
|
||||
asynchronous commits that do not require the disk I/O to
|
||||
complete before the transaction commit completes.
|
||||
The problem with this is that your application can
|
||||
potentially crash before a transaction has been
|
||||
completely written to disk. This represents a loss of
|
||||
data, which is to say the data is not durable.
|
||||
</p>
|
||||
<p>
|
||||
Replication can help with your data durability in a
|
||||
couple of ways. Most importantly, replication allows you to
|
||||
<span class="emphasis"><em>commit to the network</em></span>. This means
|
||||
that when your Master commits a transaction, the results
|
||||
of that commit are sent to one or more nodes available
|
||||
over the network. Consequently, multiple disks, disk
|
||||
controllers, power supplies, and CPUs are used to ensure
|
||||
the data modification makes it to stable storage.
|
||||
</p>
|
||||
<p>
|
||||
Usually JE makes the commit operation on the Master
|
||||
wait until it receives acknowledgements from some number
|
||||
of electable nodes before returning from the
|
||||
operation. However, if you want to increase write
|
||||
throughput, you can configure your Master to proceed
|
||||
without acknowledgements, and so return immediately from
|
||||
the commit operation (once the commit operation has met
|
||||
the local durability requirement). The price that you pay
|
||||
for this is a reduced durability guarantee. How reduced
|
||||
the guarantee is, is a function of the number of electable
|
||||
nodes in your replication group (the more you have, the
|
||||
higher your durability guarantee is) and the quality and
|
||||
stability of your network.
|
||||
</p>
|
||||
<p>
|
||||
Alternatively, you can obtain an
|
||||
extremely high durability guarantee by configuring the Master
|
||||
to wait for all electable nodes to acknowledge a commit
|
||||
operation before returning from the operation. The price
|
||||
you pay for this very high guarantee is greatly reduced
|
||||
write throughput.
|
||||
</p>
|
||||
<p>
|
||||
For information on configuring and managing durability
|
||||
guarantees for your replicated application, see
|
||||
<a class="xref" href="txn-management.html#durability" title="Managing Durability">Managing Durability</a>.
|
||||
</p>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="consistency-intro"></a>Managing Data Consistency</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
Data consistency means that the data you thought you
|
||||
wrote to your environment is in fact written to your
|
||||
environment. It also means that you will never find
|
||||
partial records written to your environment.
|
||||
</p>
|
||||
<p>
|
||||
In a replicated application, consistency also means that
|
||||
data which is available on the Master is also available
|
||||
on the Replicas.
|
||||
</p>
|
||||
<p>
|
||||
A simple transactional application offers consistency
|
||||
guarantees that are enforced when you commit a
|
||||
transaction. Your replicated application also offers this
|
||||
consistency guarantee (because it is also a transactional
|
||||
application). For this reason, the environment on the
|
||||
Master is always absolutely consistent. But beyond that, you need to manage
|
||||
consistency for data across all the nodes in your
|
||||
replication group.
|
||||
</p>
|
||||
<p>
|
||||
When you commit a transaction on the Master, your
|
||||
Replica nodes may or may not have the data changes
|
||||
performed by that transaction at the end of the commit.
|
||||
Whether they do depends on how high a durability
|
||||
guarantee you implemented for your Master (see the
|
||||
previous section). If, for example, you configured your
|
||||
Master to require acknowledgements from all electable
|
||||
nodes before returning from the commit, then the data
|
||||
will be consistently available across all of those nodes
|
||||
in the replication group, although not necessarily by
|
||||
secondary nodes. However, if you configured the Master
|
||||
such that no acknowledgements are necessary, then your
|
||||
data is probably not consistent across the replication
|
||||
group.
|
||||
</p>
|
||||
<p>
|
||||
To ensure that read transactions on the Replicas see a
|
||||
sufficiently consistent view of the environment, you can
|
||||
set a consistency policy for each transaction. This
|
||||
policy describes how current the Replica must be before a
|
||||
transaction can be initiated on it. If the Replica is not
|
||||
current enough, the start of the transaction is delayed
|
||||
until the Replica has caught up.
|
||||
</p>
|
||||
<p>
|
||||
There are two possible consistency policies. First, there
|
||||
is a time-based policy that describes how far back in
|
||||
time the Replica is allowed to lag behind the Master.
|
||||
Secondly, you can use a commit-based consistency
|
||||
policy that is based on the commit of a specified
|
||||
transaction. This policy is used to ensure the Replica is
|
||||
at least current enough to have the changes made by a
|
||||
specific transaction, and by all transactions committed
|
||||
prior to the specified transaction. The start of a
|
||||
transaction on a Replica can be delayed until the Replica
|
||||
can meet the consistency policy defined for that transaction.
|
||||
</p>
|
||||
<p>
|
||||
This means that a stringent consistency policy can affect
|
||||
your Replica's read throughput. Transactions, even
|
||||
read-only transactions, cannot begin until the Replica is
|
||||
consistent <span class="emphasis"><em>enough</em></span>. So if you have a
|
||||
Replica that has lagged far behind the Master, and which
|
||||
is having trouble catching up due to network latency or
|
||||
other issues, then read requests may stall, and perhaps
|
||||
even time out, which will affect the latency of your
|
||||
Replica's read requests, and perhaps even its
|
||||
overall availability for read requests. For this reason,
|
||||
give careful consideration to how well you want your
|
||||
Replica to perform on reads, versus how consistent you
|
||||
want the Replica to be with other nodes in the
|
||||
replication group.
|
||||
</p>
|
||||
<p>
|
||||
For more information on managing consistency in your
|
||||
replicated application, see
|
||||
<a class="xref" href="consistency.html" title="Managing Consistency">Managing Consistency</a>.
|
||||
</p>
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="introduction.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="introduction.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="lifecycle.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Chapter 1. Introduction </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Replication Group Life Cycle</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
111
docs/ReplicationGuide/dbbackup.html
Normal file
111
docs/ReplicationGuide/dbbackup.html
Normal file
|
|
@ -0,0 +1,111 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Backing up a Replicated Application</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB, Java Edition High Availability Applications" />
|
||||
<link rel="up" href="utilities.html" title="Chapter 4. Utilities" />
|
||||
<link rel="prev" href="logfile-restore.html" title="Restoring Log Files" />
|
||||
<link rel="next" href="enablerep.html" title="Converting Existing Environments for Replication" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Backing up a Replicated Application</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="logfile-restore.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 4. Utilities</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="enablerep.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="dbbackup"></a>Backing up a Replicated Application</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
In a stand-alone, non-replicated JE application, the log is
|
||||
strictly append only. You use the <a class="ulink" href="../java/com/sleepycat/je/util/DbBackup.html" target="_top">DbBackup</a> class to help
|
||||
applications coordinate while database operations are
|
||||
continuing to add to the log. This helper class does this by
|
||||
defining the log files needed for a consistent backup, and then freezes
|
||||
all changes to those files, including any changes that might be
|
||||
made by JE background operations. The application can copy
|
||||
that defined set of files and finish operation without checking
|
||||
for the ongoing creation of new files. Also, there will be no
|
||||
need to check for a newer version of the last file on the next
|
||||
backup.
|
||||
</p>
|
||||
<p>
|
||||
When you are using JE HA, however, log files other than the
|
||||
last log file might be modified as part of the HA sync-up
|
||||
operation. Though a rare occurrence, such
|
||||
modifications would invalidate the backup because there is the
|
||||
chance that files are modified after being copied.
|
||||
</p>
|
||||
<p>
|
||||
If this happens, <a class="ulink" href="../java/com/sleepycat/je/util/DbBackup.html#endBackup()" target="_top">DbBackup.endBackup()</a> throws a
|
||||
<a class="ulink" href="../java/com/sleepycat/je/rep/LogOverwriteException.html" target="_top">LogOverwriteException</a>. Upon encountering this exception, the
|
||||
backup files should be discarded and a new set of backup files
|
||||
created.
|
||||
</p>
|
||||
<p>
|
||||
For example:
|
||||
</p>
|
||||
<pre class="programlisting"> for (int i=0; i < BACKUP_RETRIES; i++) {
|
||||
final ReplicatedEnvironment repEnv = ...;
|
||||
final DbBackup backupHelper = new DbBackup(repEnv);
|
||||
|
||||
backupHelper.startBackup();
|
||||
String[] filesForBackup =
|
||||
backupHelper.getLogFilesInBackupSet();
|
||||
|
||||
/* Copy the files to archival storage. */
|
||||
myApplicationCopyMethod(filesForBackup);
|
||||
|
||||
try {
|
||||
backupHelper.endBackup();
|
||||
break;
|
||||
} catch (LogOverwriteException e) {
|
||||
/* Remove backed up files. */
|
||||
myApplicationCleanupMethod();
|
||||
continue;
|
||||
} finally {
|
||||
repEnv.close();
|
||||
}
|
||||
} </pre>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="logfile-restore.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="utilities.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="enablerep.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Restoring Log Files </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Converting Existing Environments for Replication</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
331
docs/ReplicationGuide/election-override.html
Normal file
331
docs/ReplicationGuide/election-override.html
Normal file
|
|
@ -0,0 +1,331 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Appendix A. Managing a Failure of the Majority</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB, Java Edition High Availability Applications" />
|
||||
<link rel="up" href="index.html" title="Getting Started with Berkeley DB, Java Edition High Availability Applications" />
|
||||
<link rel="prev" href="groupreset.html" title="Resetting a Replication Group" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Appendix A. Managing a Failure of the Majority</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="groupreset.html">Prev</a> </td>
|
||||
<th width="60%" align="center"> </th>
|
||||
<td width="20%" align="right"> </td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="appendix" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title"><a id="election-override"></a>Appendix A. Managing a Failure of the Majority</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
Normal operation of JE HA requires that at least a simple majority
|
||||
of electable nodes be available to form a quorum for election of a
|
||||
new Master, or when committing a transaction with default
|
||||
durability requirements. The number of electable nodes (the
|
||||
Electable Group Size) is obtained from persistent internal metadata
|
||||
that is stored in the environment and replicated across all
|
||||
members. See <a class="xref" href="lifecycle.html" title="Replication Group Life Cycle">Replication Group Life Cycle</a> for details.
|
||||
</p>
|
||||
<p>
|
||||
Under exceptional circumstances, a simple majority of electable nodes may
|
||||
become unavailable for some period of time. With only a minority
|
||||
of electable nodes available, the overall availability of the group can be
|
||||
adversely affected. For example, the group may be unavailable for
|
||||
writes because a master cannot be elected. Also, the Master may be
|
||||
unable to satisfy the durability requirements for a transaction
|
||||
commit. The group may also be unavailable for reads, because the
|
||||
absence of a Master might cause a Replica to be unable to meet
|
||||
consistency requirements.
|
||||
</p>
|
||||
<p>
|
||||
To deal with this exceptional circumstance
|
||||
— especially if the situation is likely to persist for an
|
||||
unacceptably long period of time — JE HA provides a
|
||||
mechanism by which you can modify the way in which the number of
|
||||
electable nodes, and consequently the quorum requirements for
|
||||
elections and commit acknowledgments, is calculated. The escape
|
||||
mechanism provides a way to override the normal computation of the
|
||||
Electable Group Size. The override is accomplished by specifying
|
||||
the size using the mutable replication configuration parameter
|
||||
<a class="ulink" href="../java/com/sleepycat/je/rep/ReplicationMutableConfig.html#ELECTABLE_GROUP_SIZE_OVERRIDE" target="_top">ELECTABLE_GROUP_SIZE_OVERRIDE</a>.
|
||||
</p>
|
||||
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
|
||||
<h3 class="title">Note</h3>
|
||||
<p>
|
||||
You should use this parameter sparingly, if at all. Overriding
|
||||
your Electable Group Size can have the consequence of allowing
|
||||
your replication group's election participants to elect two Masters
|
||||
simultaneously. This is especially likely to occur if a
|
||||
majority of the nodes are unavailable due to a network
|
||||
partition event, and so all nodes are running but are simply
|
||||
not communicating with one another.
|
||||
</p>
|
||||
<p>
|
||||
<span class="emphasis"><em>Be very cautious when using this configuration
|
||||
option.</em></span>
|
||||
</p>
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="override-groupsize"></a>Overriding the Electable Group Size</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="toc">
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="election-override.html#set-gsize-override">Setting the Override</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="election-override.html#gsize-override-restore">Restoring the Default State</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="election-override.html#override-example">Override Example</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</div>
|
||||
<p>
|
||||
When you set <a class="ulink" href="../java/com/sleepycat/je/rep/ReplicationMutableConfig.html#ELECTABLE_GROUP_SIZE_OVERRIDE" target="_top">ELECTABLE_GROUP_SIZE_OVERRIDE</a> to a non-zero value, the
|
||||
number that you provide identifies the number of electable nodes that
|
||||
are required to meet quorum requirements. This means that the
|
||||
internally stored Electable Group Size value is ignored (but
|
||||
not changed) when this option is non-zero. By setting
|
||||
<a class="ulink" href="../java/com/sleepycat/je/rep/ReplicationMutableConfig.html#ELECTABLE_GROUP_SIZE_OVERRIDE" target="_top">ELECTABLE_GROUP_SIZE_OVERRIDE</a> to the number of electable nodes known to be
|
||||
available, the remaining replication group participants can
|
||||
make forward progress, both in terms of electing a new
|
||||
Master (if this is required) and in terms of meeting durability
|
||||
and consistency requirements.
|
||||
</p>
|
||||
<p>
|
||||
When this option is zero (0), then the node will behave
|
||||
normally, and the internal Electable Group Size is honored by
|
||||
the node. This is the default value and behavior.
|
||||
</p>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="set-gsize-override"></a>Setting the Override</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
To override the internal Electable Group Size value:
|
||||
</p>
|
||||
<div class="orderedlist">
|
||||
<ol type="1">
|
||||
<li>
|
||||
<p>
|
||||
Verify that the simple majority of electable nodes are in fact
|
||||
down and cannot elect their own independent Master.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Set <a class="ulink" href="../java/com/sleepycat/je/rep/ReplicationMutableConfig.html#ELECTABLE_GROUP_SIZE_OVERRIDE" target="_top">ELECTABLE_GROUP_SIZE_OVERRIDE</a> to the number of
|
||||
electable nodes known to be available. For best
|
||||
results, set this override on all available
|
||||
electable nodes.
|
||||
</p>
|
||||
<p>
|
||||
It might be sufficient to set <a class="ulink" href="../java/com/sleepycat/je/rep/ReplicationMutableConfig.html#ELECTABLE_GROUP_SIZE_OVERRIDE" target="_top">ELECTABLE_GROUP_SIZE_OVERRIDE</a>
|
||||
on just one electable node in order to hold an election, because
|
||||
the proposer at that one node can conclude the
|
||||
election. However, if the election results in
|
||||
Master that is not configured with this override, it
|
||||
might result in <a class="ulink" href="../java/com/sleepycat/je/rep/InsufficientAcksException.html" target="_top">InsufficientAcksException</a>s at the Master.
|
||||
So, again, set the override on all available
|
||||
electable nodes.
|
||||
</p>
|
||||
</li>
|
||||
</ol>
|
||||
</div>
|
||||
<p>
|
||||
Having set the override, the available electable members of the
|
||||
replication group can now meet quorum requirements.
|
||||
</p>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="gsize-override-restore"></a>Restoring the Default State</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
Having restored the group to a functioning state by use of
|
||||
the <a class="ulink" href="../java/com/sleepycat/je/rep/ReplicationMutableConfig.html#ELECTABLE_GROUP_SIZE_OVERRIDE" target="_top">ELECTABLE_GROUP_SIZE_OVERRIDE</a> override, it is desirable
|
||||
to return the group to its normal state as soon as possible. The
|
||||
normal operating state is one where the Electable Group
|
||||
Size is maintained by JE HA, and the override is no longer
|
||||
used.
|
||||
</p>
|
||||
<p>
|
||||
To restore the group to its normal operational state, do
|
||||
one of the following:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
Remove from the group any electable nodes that you
|
||||
know will be down for an extended period of time.
|
||||
Remove the nodes using the
|
||||
<a class="ulink" href="../java/com/sleepycat/je/rep/util/ReplicationGroupAdmin.html#removeMember(java.lang.String)" target="_top">ReplicationGroupAdmin.removeMember()</a> API.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Bring up electable nodes as they once again come on
|
||||
line, so that they can join the functioning group.
|
||||
This must be done carefully one node at a time in
|
||||
order to avoid the small possibility that a majority of the
|
||||
downed nodes hold an election amongst themselves
|
||||
and elect a second Master.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Perform some combination of node removal and
|
||||
bringing up nodes which were previously down.
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
<p>
|
||||
As soon as there is a sufficient number of electable nodes
|
||||
up and running that election quorum requirements can be met in the
|
||||
absence of the override, the override can be removed, and
|
||||
normal HA operations resumed.
|
||||
</p>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="override-example"></a>Override Example</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
Consider a group consisting of 5 electable nodes:
|
||||
<code class="literal">n1</code>-<code class="literal">n5</code>. Suppose a
|
||||
simple majority of the nodes
|
||||
(<code class="literal">n3</code>-<code class="literal">n5</code>) have become
|
||||
unavailable.
|
||||
</p>
|
||||
<p>
|
||||
If one of the nodes in
|
||||
<code class="literal">n3</code>-<code class="literal">n5</code> was the
|
||||
Master, then nodes <code class="literal">n1</code> and
|
||||
<code class="literal">n2</code> will try to hold an election, and
|
||||
fail due to the lack of a quorum. We now carry out the steps described, above:
|
||||
</p>
|
||||
<div class="orderedlist">
|
||||
<ol type="1">
|
||||
<li>
|
||||
<p>
|
||||
Verify that <code class="literal">n3</code>-<code class="literal">n5</code> are down.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Set <a class="ulink" href="../java/com/sleepycat/je/rep/ReplicationMutableConfig.html#ELECTABLE_GROUP_SIZE_OVERRIDE" target="_top">ELECTABLE_GROUP_SIZE_OVERRIDE</a> to 2. Do this
|
||||
at both <code class="literal">n1</code> and <code class="literal">n2</code>.
|
||||
You can do this dynamically using JConsole, or by
|
||||
setting the property in the <code class="filename">je.properties</code> file and
|
||||
restarting the node.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<code class="literal">n1</code> and <code class="literal">n2</code>
|
||||
will choose a new Master, say, <code class="literal">n1</code>.
|
||||
<code class="literal">n1</code> can now process write
|
||||
operations, and <code class="literal">n2</code> can
|
||||
acknowledge transaction commits.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
Suppose that <code class="literal">n3</code> is now repaired.
|
||||
You can bring it back online and it will
|
||||
automatically locate the new Master and join the
|
||||
group. As is normal, it will catch up to
|
||||
<code class="literal">n1</code> and <code class="literal">n2</code> in
|
||||
the replication stream, and then begin
|
||||
acknowledging commits as requested by
|
||||
<code class="literal">n1</code>.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
We now have three electable nodes that are operational. Because
|
||||
we have a true simple majority of electable nodes available, we
|
||||
can now reset <a class="ulink" href="../java/com/sleepycat/je/rep/ReplicationMutableConfig.html#ELECTABLE_GROUP_SIZE_OVERRIDE" target="_top">ELECTABLE_GROUP_SIZE_OVERRIDE</a> to 0
|
||||
(do this on <code class="literal">n1</code> and <code class="literal">n2</code>),
|
||||
which causes the replication group to resume normal
|
||||
operations. Note that <code class="literal">n1</code> remains
|
||||
the Master.
|
||||
</p>
|
||||
</li>
|
||||
</ol>
|
||||
</div>
|
||||
<p>
|
||||
If <code class="literal">n2</code> was the Master at the time of the
|
||||
failure, then the situation is similar, except that an
|
||||
election is not held. In this case, <code class="literal">n2</code> will continue to
|
||||
remain the Master throughout the entire process described
|
||||
above. However, <code class="literal">n2</code> might not be able to meet quorum
|
||||
requirements for transaction commits until step 2 (above) is
|
||||
performed.
|
||||
</p>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="groupreset.html">Prev</a> </td>
|
||||
<td width="20%" align="center"> </td>
|
||||
<td width="40%" align="right"> </td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Resetting a Replication Group </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> </td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
140
docs/ReplicationGuide/enablerep.html
Normal file
140
docs/ReplicationGuide/enablerep.html
Normal file
|
|
@ -0,0 +1,140 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Converting Existing Environments for Replication</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB, Java Edition High Availability Applications" />
|
||||
<link rel="up" href="utilities.html" title="Chapter 4. Utilities" />
|
||||
<link rel="prev" href="dbbackup.html" title="Backing up a Replicated Application" />
|
||||
<link rel="next" href="monitors.html" title="Chapter 5. Writing Monitor Nodes" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Converting Existing Environments for Replication</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="dbbackup.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 4. Utilities</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="monitors.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="enablerep"></a>Converting Existing Environments for Replication</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
JE HA environments log files contain information and data
|
||||
used only by replication. Non-replicated environments are
|
||||
lacking this information, so in order to use a
|
||||
previously-existing non-replicated environment in an HA
|
||||
application, it must undergo a one time conversion.
|
||||
</p>
|
||||
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
|
||||
<h3 class="title">Note</h3>
|
||||
<p>
|
||||
If you try to open a non-replicated environment as a
|
||||
replicated environment, the operation will throw an
|
||||
<a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/UnsupportedOperationException.html" target="_top">UnsupportedOperationException</a>. This is the only way your
|
||||
code can tell if an environment needs to be converted.
|
||||
</p>
|
||||
</div>
|
||||
<p>
|
||||
You use the <a class="ulink" href="../java/com/sleepycat/je/rep/util/DbEnableReplication.html" target="_top">DbEnableReplication</a> class to perform this
|
||||
one-time conversion. This class is particularly useful if you
|
||||
want to prototype a standalone transactional application, and
|
||||
then add in replication after the transactional application is
|
||||
working as desired.
|
||||
</p>
|
||||
<p>
|
||||
The conversion process is one-way; once an environment
|
||||
directory is converted, the rules that govern
|
||||
<a class="ulink" href="../java/com/sleepycat/je/rep/ReplicatedEnvironment.html" target="_top">ReplicatedEnvironment</a> apply. This means the environment can
|
||||
no longer be opened for writes by a standalone <a class="ulink" href="../java/com/sleepycat/je/Environment.html" target="_top">Environment</a> handle
|
||||
(however, it still can be opened by a standalone
|
||||
<a class="ulink" href="../java/com/sleepycat/je/Environment.html" target="_top">Environment</a> handle in read-only mode).
|
||||
</p>
|
||||
<p>
|
||||
Note that <a class="ulink" href="../java/com/sleepycat/je/rep/util/DbEnableReplication.html" target="_top">DbEnableReplication</a> only adds a minimum amount of
|
||||
replication metadata. The conversion process is not in any way
|
||||
dependent on the size of the environment you are converting.
|
||||
</p>
|
||||
<p>
|
||||
The converted environment can be used to start a new
|
||||
replication group. After conversion, the environment can be
|
||||
opened as a <a class="ulink" href="../java/com/sleepycat/je/rep/ReplicatedEnvironment.html" target="_top">ReplicatedEnvironment</a>. Additional nodes that join
|
||||
the group are then populated with data from the converted
|
||||
environment.
|
||||
</p>
|
||||
<p>
|
||||
For example:
|
||||
</p>
|
||||
<pre class="programlisting">// Create the first node using an existing environment
|
||||
DbEnableReplication converter =
|
||||
new DbEnableReplication(envDirMars, // env home dir
|
||||
"UniversalRepGroup", // group name
|
||||
"nodeMars", // node name
|
||||
"mars:5001"); // node host,port
|
||||
converter.convert();
|
||||
|
||||
ReplicatedEnvironment nodeMars =
|
||||
new ReplicatedEnvironment(envDirMars, ...);
|
||||
|
||||
// Bring up additional nodes, which will be initialized from
|
||||
// nodeMars.
|
||||
ReplicationConfig repConfig = new ReplicationConfig();
|
||||
try {
|
||||
repConfig.setGroupName("UniversalRepGroup");
|
||||
repConfig.setNodeName("nodeVenus");
|
||||
repConfig.setNodeHostPort("venus:5008");
|
||||
repConfig.setHelperHosts("mars:5001");
|
||||
|
||||
nodeVenus = new ReplicatedEnvironment(envDirVenus,
|
||||
repConfig,
|
||||
envConfig);
|
||||
} catch (InsufficientLogException insufficientLogEx) {
|
||||
|
||||
// log files will be copied from another node in the group
|
||||
NetworkRestore restore = new NetworkRestore();
|
||||
restore.execute(insufficientLogEx, new NetworkRestoreConfig());
|
||||
|
||||
// try opening the node now
|
||||
nodeVenus = new ReplicatedEnvironment(envDirVenus,
|
||||
repConfig,
|
||||
envConfig);
|
||||
} </pre>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="dbbackup.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="utilities.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="monitors.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Backing up a Replicated Application </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Chapter 5. Writing Monitor Nodes</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
179
docs/ReplicationGuide/events.html
Normal file
179
docs/ReplicationGuide/events.html
Normal file
|
|
@ -0,0 +1,179 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>Listening for Events</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB, Java Edition High Availability Applications" />
|
||||
<link rel="up" href="monitors.html" title="Chapter 5. Writing Monitor Nodes" />
|
||||
<link rel="prev" href="monitors.html" title="Chapter 5. Writing Monitor Nodes" />
|
||||
<link rel="next" href="repexample.html" title="Chapter 6. Replication Examples" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Listening for Events</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="monitors.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 5. Writing Monitor Nodes</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="repexample.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="events"></a>Listening for Events</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
One of the things the <a class="ulink" href="../java/com/sleepycat/je/rep/monitor/Monitor.html" target="_top">Monitor</a> class allows you to do is to
|
||||
listen for certain events that occur in the composition of the
|
||||
replication group. Your Monitor can be notified of these events
|
||||
by running an event listener using <a class="ulink" href="../java/com/sleepycat/je/rep/monitor/Monitor.html#startListener(com.sleepycat.je.rep.monitor.MonitorChangeListener)" target="_top">Monitor.startListener()</a>.
|
||||
For example:
|
||||
</p>
|
||||
<p>
|
||||
<code class="methodname">Monitor.startListener()</code> takes a single
|
||||
argument, and that is an instance of <a class="ulink" href="../java/com/sleepycat/je/rep/monitor/MonitorChangeListener.html" target="_top">MonitorChangeListener</a>.
|
||||
<code class="classname">MonitorChangeListener</code> is an interface
|
||||
that you implement for the purpose of handling replication
|
||||
group events.
|
||||
</p>
|
||||
<p>
|
||||
There are four events that the change listener can be notified
|
||||
of. Each of these are represented by a unique class:
|
||||
</p>
|
||||
<div class="orderedlist">
|
||||
<ol type="1">
|
||||
<li>
|
||||
<p>
|
||||
<a class="ulink" href="../java/com/sleepycat/je/rep/monitor/GroupChangeEvent.html" target="_top">GroupChangeEvent</a>
|
||||
</p>
|
||||
<p>
|
||||
A new instance of this event is generated each time
|
||||
an electable or monitor node, but not a secondary
|
||||
node, is added or removed from the replication group.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<a class="ulink" href="../java/com/sleepycat/je/rep/monitor/NewMasterEvent.html" target="_top">NewMasterEvent</a>
|
||||
</p>
|
||||
<p>
|
||||
A new instance of this event is generated each time a
|
||||
new Master is elected.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<a class="ulink" href="../java/com/sleepycat/je/rep/monitor/JoinGroupEvent.html" target="_top">JoinGroupEvent</a>
|
||||
</p>
|
||||
<p>
|
||||
A new instance of this event is generated each time an
|
||||
electable or secondary node, but not a monitor node,
|
||||
joins a group. The event is generated on a "best
|
||||
effort" basis. It may not be generated, for example,
|
||||
if the joining node was unable to communicate with the
|
||||
monitor due to a network problem. The application must
|
||||
be resilient in the face of such missing events.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<a class="ulink" href="../java/com/sleepycat/je/rep/monitor/LeaveGroupEvent.html" target="_top">LeaveGroupEvent</a>
|
||||
</p>
|
||||
<p>
|
||||
A new instance of this event is generated each time an
|
||||
electable or secondary node, but not a monitor node,
|
||||
node leaves the group. The event is generated on a
|
||||
"best effort" basis. It may not be generated if the
|
||||
node leaving the group dies (for example, it was
|
||||
killed) before it has a chance to generate the event,
|
||||
or if the node was unable to communicate with the
|
||||
monitor due to a network problem. The application must
|
||||
be resilient in the face of such missing events.
|
||||
</p>
|
||||
</li>
|
||||
</ol>
|
||||
</div>
|
||||
<p>
|
||||
For example, an implementation of the <a class="ulink" href="../java/com/sleepycat/je/rep/monitor/MonitorChangeListener.html" target="_top">MonitorChangeListener</a>
|
||||
interface might be:
|
||||
</p>
|
||||
<pre class="programlisting">class MyChangeListener implements MonitorChangeListener {
|
||||
|
||||
public void notify(NewMasterEvent newMasterEvent) {
|
||||
|
||||
String newNodeName = newMasterEvent.getNodeName();
|
||||
|
||||
InetSocketAddress newMasterAddr =
|
||||
newMasterEvent.getSocketAddress();
|
||||
String newMasterHostName = newMasterAddr.getHostName();
|
||||
int newMasterPort = newMasterAddr.getPort();
|
||||
|
||||
// Do something with this information here.
|
||||
}
|
||||
|
||||
public void notify(GroupChangeEvent groupChangeEvent) {
|
||||
ReplicationGroup repGroup = groupChangeEvent.getRepGroup();
|
||||
|
||||
// Do something with the new ReplicationGroup composition here.
|
||||
}
|
||||
|
||||
...
|
||||
|
||||
} </pre>
|
||||
<p>
|
||||
You can then start the Monitor listener as follows:
|
||||
</p>
|
||||
<pre class="programlisting"> // Initialize the monitor node config
|
||||
ReplicationConfig config =
|
||||
new ReplicationConfig("MyRepGroupName",
|
||||
"mon1",
|
||||
"monhost1.acme.com:7000");
|
||||
config.setNodeType(NodeType.MONITOR);
|
||||
config.setHelperHosts("node1.acme.com:5000,node2.acme.com:5000");
|
||||
|
||||
Monitor monitor = new Monitor(config);
|
||||
|
||||
// If the monitor has not been registered as a member of the
|
||||
// group, register it now. register() returns the current node
|
||||
// that is the master.
|
||||
ReplicationNode currentMaster = monitor.register();
|
||||
|
||||
<strong class="userinput"><code>// Start up the listener, so that it can be used to track changes
|
||||
// in the master node, or group composition.
|
||||
monitor.startListener(new MyChangeListener());</code></strong> </pre>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="monitors.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="monitors.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="repexample.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Chapter 5. Writing Monitor Nodes </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Chapter 6. Replication Examples</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
318
docs/ReplicationGuide/exceptions.html
Normal file
318
docs/ReplicationGuide/exceptions.html
Normal file
|
|
@ -0,0 +1,318 @@
|
|||
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||||
<title>HA Exceptions</title>
|
||||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB, Java Edition High Availability Applications" />
|
||||
<link rel="up" href="progoverview.html" title="Chapter 2. Replication API First Steps" />
|
||||
<link rel="prev" href="progoverview.html" title="Chapter 2. Replication API First Steps" />
|
||||
<link rel="next" href="repenvironmentopen.html" title="Opening a Replicated Environment" />
|
||||
</head>
|
||||
<body>
|
||||
<div xmlns="" class="navheader">
|
||||
<div class="libver">
|
||||
<p>Library Version 12.2.7.5</p>
|
||||
</div>
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">HA Exceptions</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="progoverview.html">Prev</a> </td>
|
||||
<th width="60%" align="center">Chapter 2. Replication API First Steps</th>
|
||||
<td width="20%" align="right"> <a accesskey="n" href="repenvironmentopen.html">Next</a></td>
|
||||
</tr>
|
||||
</table>
|
||||
<hr />
|
||||
</div>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="exceptions"></a>HA Exceptions</h2>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="toc">
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="exceptions.html#master-exceptions">Master-Specific HA Exceptions</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="exceptions.html#replica-exceptions">Replica-Specific HA Exceptions</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect2">
|
||||
<a href="exceptions.html#handleexception">Replicated Environment Handle-Specific Exceptions</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</div>
|
||||
<p>
|
||||
JE HA requires you to manage more error situations that you
|
||||
would have to if you were writing a non-replicated application.
|
||||
These error situations translate to additional exceptions that
|
||||
you must contend with in your code. Before continuing with our
|
||||
description of how to write a replicated application, it is
|
||||
useful to review the HA-specific exceptions that your
|
||||
application must manage.
|
||||
</p>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="master-exceptions"></a>Master-Specific HA Exceptions</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
There are two exceptions that you can see on a Master node,
|
||||
and which you will not see anywhere else. They are:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
<a class="ulink" href="../java/com/sleepycat/je/rep/InsufficientReplicasException.html" target="_top">InsufficientReplicasException</a>
|
||||
</p>
|
||||
<p>
|
||||
This exception can be raised on a transaction begin or commit. It means that the
|
||||
Master cannot successfully commit a transaction, or begin one, because it is not in contact
|
||||
with enough Electable Replicas. The number of Electable Replicas required to successfully commit
|
||||
the transaction is a function of the durability policy that
|
||||
you have set for the transaction. See
|
||||
<a class="xref" href="txn-management.html#durability" title="Managing Durability">Managing Durability</a>
|
||||
for more information.
|
||||
</p>
|
||||
<p>
|
||||
If raised on a transaction commit operation, this
|
||||
exception means that the transaction has not been
|
||||
committed. Instead, it has been marked as invalid.
|
||||
In response to this exception, your application
|
||||
must at a minimum abort the transaction. It is up
|
||||
to you whether you want to retry the transaction at
|
||||
some later time when more Replicas are in contact
|
||||
with the Master.
|
||||
</p>
|
||||
<p>
|
||||
If raised on a transaction begin operation, this
|
||||
exception means that the transaction has not begun.
|
||||
If the application intended to initiate a read-only
|
||||
transaction on a Master, it can avoid this
|
||||
exception by ensuring that the transaction is
|
||||
configured to not require any acknowledgments. For
|
||||
information on configuring acknowledgments, see
|
||||
<a class="xref" href="txn-management.html#managingacks" title="Managing Acknowledgements">Managing Acknowledgements</a>.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<a class="ulink" href="../java/com/sleepycat/je/rep/InsufficientAcksException.html" target="_top">InsufficientAcksException</a>
|
||||
</p>
|
||||
<p>
|
||||
This exception can be raised on a transaction commit. It means that the
|
||||
Master has successfully committed the transaction locally, but it has not
|
||||
received enough acknowledgements from its Electable Replicas in the timeframe
|
||||
allocated for acknowledgements to be received.
|
||||
</p>
|
||||
<p>
|
||||
The application should respond to this exception in such a way as to alert
|
||||
the administrator that there might be a problem with the health of the
|
||||
network or the nodes participating in the replication group.
|
||||
</p>
|
||||
<p>
|
||||
For information on how to manage acknowledgement policies, see
|
||||
<a class="xref" href="txn-management.html#managingacks" title="Managing Acknowledgements">Managing Acknowledgements</a>.
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="replica-exceptions"></a>Replica-Specific HA Exceptions</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
The exceptions that you can see on a Replica, and nowhere else, are:
|
||||
</p>
|
||||
<div class="itemizedlist">
|
||||
<ul type="disc">
|
||||
<li>
|
||||
<p>
|
||||
<a class="ulink" href="../java/com/sleepycat/je/rep/ReplicaConsistencyException.html" target="_top">ReplicaConsistencyException</a>
|
||||
</p>
|
||||
<p>
|
||||
Indicates that the Replica was unable to meet the defined consistency
|
||||
requirements in the allocated period of time.
|
||||
</p>
|
||||
<p>
|
||||
If this exception is encountered frequently, it indicates that the
|
||||
consistency policy requirements are too strict and cannot be met routinely
|
||||
given the load being placed on the system and the hardware resources that
|
||||
are available to service the load. The exception may also indicate that
|
||||
there is a network related issue that is preventing the Replica from
|
||||
communicating with the Master and keeping up with the replication stream.
|
||||
</p>
|
||||
<p>
|
||||
In response to this exception, your application can either attempt to retry
|
||||
the transaction, or you can relax your application's consistency
|
||||
requirements until the transaction can successfully complete.
|
||||
</p>
|
||||
<p>
|
||||
For information on managing consistency policies, see
|
||||
<a class="xref" href="consistency.html" title="Managing Consistency">Managing Consistency</a>.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<a class="ulink" href="../java/com/sleepycat/je/rep/ReplicaWriteException.html" target="_top">ReplicaWriteException</a>
|
||||
</p>
|
||||
<p>
|
||||
An attempt was made to perform a write operation on a Replica. The exception
|
||||
typically indicates an error in the application logic. In some extremely
|
||||
rare cases it could be the result of a transition of the node from Master to
|
||||
Replica, while a transaction was in progress.
|
||||
</p>
|
||||
<p>
|
||||
The application must abort the current transaction and redirect all
|
||||
subsequent update operations to the Master. For
|
||||
example code that performs this action, see
|
||||
<a class="xref" href="runtransaction.html" title="Example Run Transaction Class">Example Run Transaction Class</a>.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<a class="ulink" href="../java/com/sleepycat/je/rep/LockPreemptedException.html" target="_top">LockPreemptedException</a>
|
||||
</p>
|
||||
<p>
|
||||
A read lock currently held by a Replica has been preempted by an HA write
|
||||
operation. The Replica should abort and retry the read operation in response
|
||||
to this exception.
|
||||
</p>
|
||||
<p>
|
||||
Note that your application should attempt to catch the
|
||||
<a class="ulink" href="../java/com/sleepycat/je/LockConflictException.html" target="_top">LockConflictException</a> base class rather than this class because all of the
|
||||
locking exceptions are managed in the same way (abort and retry the
|
||||
transaction).
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<a class="ulink" href="../java/com/sleepycat/je/rep/DatabasePreemptedException.html" target="_top">DatabasePreemptedException</a>
|
||||
</p>
|
||||
<p>
|
||||
The database handle on a Replica was forcibly closed due to the replay of an
|
||||
<a class="ulink" href="../java/com/sleepycat/je/Environment.html#truncateDatabase(com.sleepycate.je.Transaction,java.lang.String,boolean)" target="_top">Environment.truncateDatabase()</a>, <a class="ulink" href="../java/com/sleepycat/je/Environment.html#removeDatabase(com.sleepycate.je.Transaction,java.lang.String)" target="_top">Environment.removeDatabase()</a> or
|
||||
<a class="ulink" href="../java/com/sleepycat/je/Environment.html#renameDatabase(com.sleepycate.je.Transaction,java.lang.String,java.lang.String)" target="_top">Environment.renameDatabase()</a> operation in the
|
||||
replication stream.
|
||||
</p>
|
||||
<p>
|
||||
When this exception occurs, the application must close any open Cursors and
|
||||
abort any open Transactions that are using the database, and then close the
|
||||
Database handle. If the application wishes, it may reopen the database if it
|
||||
still exists.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<a class="ulink" href="../java/com/sleepycat/je/rep/RollbackException.html" target="_top">RollbackException</a>
|
||||
</p>
|
||||
<p>
|
||||
A new master has been selected, this Replica's log is ahead of the current
|
||||
Master, but the Replica was unable to rollback without a
|
||||
recovery. As a consequence, one or more of the most recently committed
|
||||
transactions may need to be rolled back, before the Replica can synchronize
|
||||
its state with that of the current Master. This
|
||||
exception can happen if the electable Replica with the most
|
||||
recent log files was unable to participate in the
|
||||
election of the Master, perhaps because the node
|
||||
had been shut down.
|
||||
</p>
|
||||
<p>
|
||||
For details on how to handle this exception, see
|
||||
<a class="xref" href="txnrollback.html" title="Managing Transaction Rollbacks">Managing Transaction Rollbacks</a>.
|
||||
</p>
|
||||
</li>
|
||||
<li>
|
||||
<p>
|
||||
<a class="ulink" href="../java/com/sleepycat/je/rep/InsufficientLogException.html" target="_top">InsufficientLogException</a>
|
||||
</p>
|
||||
<p>
|
||||
Indicates that the log files constituting the Environment are insufficient
|
||||
and cannot be used as the basis for continuing with the replication stream
|
||||
provided by the current master.
|
||||
</p>
|
||||
<p>
|
||||
This exception generally means that the node has been down for a long enough
|
||||
time that it can not be brought up-to-date by the Master. For information on
|
||||
how to respond to this condition, see
|
||||
<a class="xref" href="logfile-restore.html" title="Restoring Log Files">Restoring Log Files</a>.
|
||||
</p>
|
||||
</li>
|
||||
</ul>
|
||||
</div>
|
||||
</div>
|
||||
<div class="sect2" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h3 class="title"><a id="handleexception"></a>Replicated Environment Handle-Specific Exceptions</h3>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>
|
||||
In addition to Master- and Replica-specific exceptions, it is possible for a
|
||||
<a class="ulink" href="../java/com/sleepycat/je/rep/ReplicatedEnvironment.html" target="_top">ReplicatedEnvironment</a> handle to throw an <a class="ulink" href="../java/com/sleepycat/je/rep/UnknownMasterException.html" target="_top">UnknownMasterException</a>. This exception
|
||||
indicates that the operation being tried requires communication with a Master, but
|
||||
the Master is not available.
|
||||
</p>
|
||||
<p>
|
||||
This exception typically indicates that there is a problem with your physical
|
||||
infrastructure. It might mean that an insufficient number of electable nodes are available to
|
||||
elect a Master, or that the current node is unable to communicate with other nodes
|
||||
due to, for example, network problems.
|
||||
</p>
|
||||
<p>
|
||||
In response to this exception, your application can try any number of corrective
|
||||
actions, from immediately retrying the operation, to logging the problem and then
|
||||
abandoning the operation, to waiting some predetermined period of time before
|
||||
attempting the operation again. Your application can also
|
||||
use the <a class="ulink" href="../java/com/sleepycat/je/rep/monitor/Monitor.html" target="_top">Monitor</a> or the <a class="ulink" href="../java/com/sleepycat/je/rep/StateChangeListener.html" target="_top">StateChangeListener</a> to be
|
||||
notified when a Master becomes available. For more
|
||||
information see <a class="xref" href="monitors.html" title="Chapter 5. Writing Monitor Nodes">Writing Monitor Nodes</a>
|
||||
or <a class="xref" href="replicawrites.html#using-statechangelistener" title="Using the StateChangeListener">Using the StateChangeListener</a>.
|
||||
</p>
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="progoverview.html">Prev</a> </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="u" href="progoverview.html">Up</a>
|
||||
</td>
|
||||
<td width="40%" align="right"> <a accesskey="n" href="repenvironmentopen.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Chapter 2. Replication API First Steps </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Opening a Replicated Environment</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
Some files were not shown because too many files have changed in this diff Show more
Loading…
Reference in a new issue