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162 lines
6.7 KiB
HTML
162 lines
6.7 KiB
HTML
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<?xml version="1.0" encoding="UTF-8" standalone="no"?>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml">
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
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<title>Secondary Indices with Transaction Applications</title>
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<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
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<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
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<link rel="start" href="index.html" title="Getting Started with Berkeley DB, Java Edition Transaction Processing" />
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<link rel="up" href="usingtxns.html" title="Chapter 3. Transaction Basics" />
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<link rel="prev" href="txncursor.html" title="Transactional Cursors" />
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<link rel="next" href="maxtxns.html" title="Configuring the Transaction Subsystem" />
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</head>
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<body>
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<div xmlns="" class="navheader">
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<div class="libver">
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<p>Library Version 12.2.7.5</p>
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</div>
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<table width="100%" summary="Navigation header">
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<tr>
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<th colspan="3" align="center">Secondary Indices with Transaction Applications</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="txncursor.html">Prev</a> </td>
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<th width="60%" align="center">Chapter 3. Transaction Basics</th>
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<td width="20%" align="right"> <a accesskey="n" href="maxtxns.html">Next</a></td>
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</tr>
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</table>
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<hr />
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</div>
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<div class="sect1" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h2 class="title" style="clear: both"><a id="txnindices"></a>Secondary Indices with Transaction Applications</h2>
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</div>
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</div>
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</div>
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<p>
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You can use transactions with your secondary indices so long as you
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<span>
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open the secondary index so that it is transactional.
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</span>
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</p>
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<p>
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All other aspects of using secondary indices with transactions are
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identical to using secondary indices without transactions. In
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addition, transaction-protecting
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<span>
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secondary cursors is performed just as you protect normal
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cursors — you simply have to make sure the cursor is
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opened using a transaction handle, and that the cursor is
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closed before the handle is either either committed or
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aborted.
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</span>
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See <a class="xref" href="txncursor.html" title="Transactional Cursors">Transactional Cursors</a> for details.
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</p>
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<p>
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Note that when you use transactions to protect your database writes, your secondary indices are protected from
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corruption because updates to the primary and the secondaries are performed in a single atomic transaction.
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</p>
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<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
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<h3 class="title">Note</h3>
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<p>
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If you are using the DPL, then be aware that
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you never have to provide a transactional
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handle when opening an index, be it a primary
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or a secondary. However, if transactions are
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enabled for your store, then all of the indexes
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that you open will be enabled for transactional
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usage. Moreover, any write operation performed
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using that index will be done using a
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transaction, regardless of whether you
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explicitly provide a transactional handle to the
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write operation.
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</p>
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<p>
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If you do not explicitly provide a transaction
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handle to DPL write operations performed on a
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transactional store, then auto commit is
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silently used for that operation.
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</p>
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</div>
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<p>
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For example:
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</p>
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<pre class="programlisting">package je.txn;
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import com.sleepycat.bind.tuple.TupleBinding;
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import com.sleepycat.je.Database;
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import com.sleepycat.je.DatabaseType;
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import com.sleepycat.je.DatabaseConfig;
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import com.sleepycat.je.DatabaseException;
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import com.sleepycat.je.Environment;
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import com.sleepycat.je.EnvironmentConfig;
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import com.sleepycat.je.SecondaryDatabase;
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import com.sleepycat.je.SecondaryConfig;
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import java.io.FileNotFoundException;
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...
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// Environment and primary database opens omitted.
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SecondaryConfig mySecConfig = new SecondaryConfig();
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mySecConfig.setAllowCreate(true);
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mySecConfig.setTransactional(true);
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SecondaryDatabase mySecDb = null;
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try {
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// A fake tuple binding that is not actually implemented anywhere.
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// The tuple binding is dependent on the data in use.
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// See the Getting Started Guide for details
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TupleBinding myTupleBinding = new MyTupleBinding();
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// Open the secondary. FullNameKeyCreator is not actually implemented
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// anywhere. See the Getting Started Guide for details.
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FullNameKeyCreator keyCreator =
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new FullNameKeyCreator(myTupleBinding);
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// Set the key creator on the secondary config object.
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mySecConfig.setKeyCreator(keyCreator);
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// Perform the actual open. Because this database is configured to be
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// transactional, the open is automatically wrapped in a transaction.
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// - myEnv is the environment handle.
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// - myDb is the primary database handle.
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String secDbName = "mySecondaryDatabase";
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mySecDb = myEnv.openSecondary(null, secDbName, null, myDb,
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mySecConfig);
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} catch (DatabaseException de) {
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// Exception handling goes here ...
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} </pre>
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</div>
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<div class="navfooter">
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<hr />
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<table width="100%" summary="Navigation footer">
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<tr>
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<td width="40%" align="left"><a accesskey="p" href="txncursor.html">Prev</a> </td>
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<td width="20%" align="center">
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<a accesskey="u" href="usingtxns.html">Up</a>
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</td>
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<td width="40%" align="right"> <a accesskey="n" href="maxtxns.html">Next</a></td>
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</tr>
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<tr>
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<td width="40%" align="left" valign="top">Transactional Cursors </td>
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<td width="20%" align="center">
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<a accesskey="h" href="index.html">Home</a>
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</td>
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<td width="40%" align="right" valign="top"> Configuring the Transaction Subsystem</td>
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</tr>
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</table>
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</div>
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</body>
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</html>
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