mirror of
https://github.com/berkeleydb/libdb.git
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207 lines
7.4 KiB
HTML
207 lines
7.4 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>Opening a Transactional Environment and Store or Database</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 Transaction Processing" />
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<link rel="up" href="enabletxn.html" title="Chapter 2. Enabling Transactions" />
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<link rel="prev" href="enabletxn.html" title="Chapter 2. Enabling Transactions" />
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<link rel="next" href="usingtxns.html" title="Chapter 3. Transaction Basics" />
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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 11.2.5.2</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">Opening a Transactional Environment and
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<span xmlns="http://www.w3.org/1999/xhtml">Store or Database</span>
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</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="enabletxn.html">Prev</a> </td>
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<th width="60%" align="center">Chapter 2. Enabling Transactions</th>
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<td width="20%" align="right"> <a accesskey="n" href="usingtxns.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="envopen"></a>Opening a Transactional Environment and
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<span>Store or Database</span>
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</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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To enable transactions for your environment, you must initialize the
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transactional subsystem. Note that doing this also initializes the
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logging subsystem. In addition, you must initialize the memory pool
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(in-memory cache). You must also initialize the locking subsystem.
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<span>
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For example, to do this with the DPL:
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</span>
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</p>
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<pre class="programlisting">package persist.txn;
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import com.sleepycat.db.DatabaseException;
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import com.sleepycat.db.Environment;
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import com.sleepycat.db.EnvironmentConfig;
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import com.sleepycat.persist.EntityStore;
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import com.sleepycat.persist.StoreConfig;
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import java.io.File;
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import java.io.FileNotFoundException;
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...
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Environment myEnv = null;
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EntityStore myStore = null;
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try {
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EnvironmentConfig myEnvConfig = new EnvironmentConfig();
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StoreConfig storeConfig = new StoreConfig();
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myEnvConfig.setInitializeCache(true);
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myEnvConfig.setInitializeLocking(true);
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myEnvConfig.setInitializeLogging(true);
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myEnvConfig.setTransactional(true);
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storeConfig.setTransactional(true);
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myEnv = new Environment(new File("/my/env/home"),
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myEnvConfig);
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myStore = new EntityStore(myEnv, "EntityStore", storeConfig);
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} catch (DatabaseException de) {
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// Exception handling goes here
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} catch (FileNotFoundException fnfe) {
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// Exception handling goes here
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}</pre>
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<p>
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And when using the base API:
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</p>
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<pre class="programlisting">package db.txn;
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import com.sleepycat.db.DatabaseException;
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import com.sleepycat.db.Environment;
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import com.sleepycat.db.EnvironmentConfig;
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import java.io.File;
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import java.io.FileNotFoundException;
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...
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Environment myEnv = null;
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try {
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EnvironmentConfig myEnvConfig = new EnvironmentConfig();
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myEnvConfig.setInitializeCache(true);
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myEnvConfig.setInitializeLocking(true);
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myEnvConfig.setInitializeLogging(true);
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myEnvConfig.setTransactional(true);
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myEnv = new Environment(new File("/my/env/home"),
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myEnvConfig);
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} catch (DatabaseException de) {
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// Exception handling goes here
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} catch (FileNotFoundException fnfe) {
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// Exception handling goes here
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}</pre>
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<p>
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You then can use the <code class="classname">Environment</code> handle to open
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your database(s) using <code class="methodname">Environment.openDatabase()</code>.
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Note that when you do this, you must set
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<code class="methodname">DatabaseConfig.setTransactional()</code>
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to <code class="literal">true</code>. Note that in effect this causes the
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database open to be transactional protected because it results in
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auto commit being used for the open (if a transaction is not explicitly
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used to protect the open).
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For example:
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</p>
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<pre class="programlisting">package db.txn;
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<strong class="userinput"><code>import com.sleepycat.db.Database;
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import com.sleepycat.db.DatabaseType;
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import com.sleepycat.db.DatabaseConfig;</code></strong>
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import com.sleepycat.db.DatabaseException;
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import com.sleepycat.db.Environment;
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import com.sleepycat.db.EnvironmentConfig;
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import java.io.File;
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import java.io.FileNotFoundException;
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...
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<strong class="userinput"><code>Database myDatabase = null;</code></strong>
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Environment myEnv = null;
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try {
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EnvironmentConfig myEnvConfig = new EnvironmentConfig();
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myEnvConfig.setInitializeCache(true);
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myEnvConfig.setInitializeLocking(true);
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myEnvConfig.setInitializeLogging(true);
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myEnvConfig.setTransactional(true);
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myEnv = new Environment(new File("/my/env/home"),
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myEnvConfig);
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<strong class="userinput"><code>// Open the database.
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DatabaseConfig dbConfig = new DatabaseConfig();
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dbConfig.setTransactional(true);
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dbConfig.setType(DatabaseType.BTREE);
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myDatabase = myEnv.openDatabase(null, // txn handle
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"sampleDatabase", // db file name
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null, // db name
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dbConfig);</code></strong>
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} catch (DatabaseException de) {
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// Exception handling goes here
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} catch (FileNotFoundException fnfe) {
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// Exception handling goes here
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}</pre>
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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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Never close a database <span> or
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store </span> that has active transactions. Make sure
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all transactions are resolved (either committed or aborted)
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before closing the database.
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</p>
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</div>
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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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|||
|
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<tr>
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|||
|
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<td width="40%" align="left"><a accesskey="p" href="enabletxn.html">Prev</a> </td>
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|||
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<td width="20%" align="center">
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|||
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<a accesskey="u" href="enabletxn.html">Up</a>
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</td>
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|
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<td width="40%" align="right"> <a accesskey="n" href="usingtxns.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">Chapter 2. Enabling Transactions </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"> Chapter 3. Transaction Basics</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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