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260 lines
8.7 KiB
HTML
260 lines
8.7 KiB
HTML
<?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>Chapter 2. Enabling Transactions</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="index.html" title="Getting Started with Berkeley DB, Java Edition Transaction Processing" />
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<link rel="prev" href="perftune-intro.html" title="Performance Tuning" />
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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 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">Chapter 2. Enabling Transactions</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="perftune-intro.html">Prev</a> </td>
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<th width="60%" align="center"> </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="chapter" 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"><a id="enabletxn"></a>Chapter 2. Enabling Transactions</h2>
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</div>
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</div>
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</div>
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<div class="toc">
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<p>
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<b>Table of Contents</b>
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</p>
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<dl>
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<dt>
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<span class="sect1">
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<a href="enabletxn.html#envopen">Opening a Transactional Environment and
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<span>Store or Database</span>
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</a>
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</span>
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</dt>
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</dl>
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</div>
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<p>
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In order to use transactions with your application, you must turn them
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on. To do this you must:
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</p>
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<div class="itemizedlist">
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<ul type="disc">
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<li>
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<p>
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Turn on transactions for your environment.
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<span>
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You do this by using the
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<code class="methodname">EnvironmentConfig.setTransactional()</code>
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method<span>, or by using the
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<code class="literal">je.env.isTransactional</code>
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<code class="filename">je.properties</code> parameter</span>.
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</span>
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</p>
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</li>
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<li>
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<p>
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If you are using the DPL, transaction-enable your stores.
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You do this by using the
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<code class="methodname">StoreConfig.setTransactional() method.</code>
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</p>
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</li>
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<li>
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<p>
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<span>
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Transaction-enable your databases.
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</span>
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<span>
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If you are using the base API, transaction-enable your databases.
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</span>
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You do this by
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<span>
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using the
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<code class="methodname">DatabaseConfig.setTransactional()</code>
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method, and then opening the database from within a transaction.
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</span>
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<span>
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Note that the common practice is for auto commit to be used to
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transaction-protect the database open. To use auto-commit, you
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must still enable transactions as described here, but you do
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not have to explicitly use a transaction when you open your
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database. An example of this is given in the next section.
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</span>
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</p>
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</li>
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</ul>
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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. For example, do this with the DPL:
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</p>
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<pre class="programlisting">package persist.txn;
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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.persist.EntityStore;
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import com.sleepycat.persist.StoreConfig;
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import java.io.File;
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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.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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}</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 je.txn;
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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 java.io.File;
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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.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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}</pre>
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<p>
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You then create and open your database(s) as you would for a non-transactional system.
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<span>
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The only difference is that 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 your database open must be
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transactional-protected. However, if you do not give the
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<code class="methodname">openDatabase()</code> method a transaction handle,
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then the open is automatically protected using auto commit.
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Typically auto commit is used for this purpose.
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For example:
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</span>
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</p>
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<pre class="programlisting">package je.txn;
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<strong class="userinput"><code>import com.sleepycat.je.Database;
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import com.sleepycat.je.DatabaseConfig;</code></strong>
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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 java.io.File;
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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.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. Create it if it does not already exist.
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DatabaseConfig dbConfig = new DatabaseConfig();
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dbConfig.setTransactional(true);
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myDatabase = myEnv.openDatabase(null,
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"sampleDatabase",
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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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}
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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>
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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="perftune-intro.html">Prev</a> </td>
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<td width="20%" align="center"> </td>
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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">Performance Tuning </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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