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165 lines
6.8 KiB
HTML
165 lines
6.8 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>Database Properties</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" />
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<link rel="up" href="databases.html" title="Chapter 7. Databases" />
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<link rel="prev" href="databases.html" title="Chapter 7. Databases" />
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<link rel="next" href="DBAdmin.html" title="Administrative Methods" />
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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">Database Properties</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="databases.html">Prev</a> </td>
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<th width="60%" align="center">Chapter 7. Databases</th>
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<td width="20%" align="right"> <a accesskey="n" href="DBAdmin.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="dbprops"></a>Database Properties</h2>
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</div>
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</div>
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</div>
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<p>You can set database properties using the <code class="classname">DatabaseConfig</code>
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class. For each of the properties that you can set, there is a
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corresponding getter method. Also, you can always retrieve the
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<code class="classname">DatabaseConfig</code> object used by your database using
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the <code class="methodname">Database.getConfig()</code> method.</p>
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<p>The database properties that you can set are:</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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<code class="methodname">DatabaseConfig.setAllowCreate()</code>
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</p>
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<p>If <code class="literal">true</code>, the database is created when it is
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opened. If false, the database open fails if the database does not
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exist. This property has no meaning if the database currently exists.
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Default is <code class="literal">false</code>.</p>
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</li>
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<li>
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<p>
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<code class="methodname">DatabaseConfig.setBtreeComparator()</code>
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</p>
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<p>Sets the class that is used to compare the keys found on two
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database records. This class is used to determine the sort order for
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two records in the database. By default, byte for byte comparison is
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used.
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For more information, see
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<span><a class="xref" href="comparator.html" title="Using Comparators">Using Comparators</a>.</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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<code class="methodname">DatabaseConfig.setDuplicateComparator()</code>
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</p>
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<p>
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Sets the class that is used to compare two duplicate records in
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the database. For more information, see
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<span><a class="xref" href="comparator.html" title="Using Comparators">Using Comparators</a>.</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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<code class="methodname">DatabaseConfig.setSortedDuplicates()</code>
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</p>
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<p>If <code class="literal">true</code>, duplicate records are allowed in the
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database. If this value is <code class="literal">false</code>, then putting a duplicate record into the database
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results in an error return from the put call.
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Note that this property can be set only at database creation time. Default is <code class="literal">false</code>.
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</p>
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<p>
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Note that your database must not support duplicates if it is to be associated with one or more
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secondary indices. Secondaries are described in <a class="xref" href="indexes.html" title="Chapter 10. Secondary Databases">Secondary Databases</a>.
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</p>
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</li>
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<li>
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<p>
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<code class="methodname">DatabaseConfig.setExclusiveCreate()</code>
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</p>
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<p>If <code class="literal">true</code>, the database open fails if the
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database currently exists. That is, the open must result in the
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creation of a new database. Default is <code class="literal">false</code>.</p>
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</li>
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<li>
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<p>
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<code class="methodname">DatabaseConfig.setReadOnly()</code>
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</p>
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<p>If true, the database is opened for read activities only.
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Default is <code class="literal">false</code>.</p>
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</li>
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<li>
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<p>
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<code class="methodname">DatabaseConfig.setTransactional()</code>
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</p>
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<p>If true, the database supports transactions.
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Default is <code class="literal">false</code>. Note that a database cannot support
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transactions if the environment is non-transactional.</p>
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</li>
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</ul>
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</div>
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<p>For example:</p>
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<a id="je_db3"></a>
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<pre class="programlisting">package je.gettingStarted;
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import com.sleepycat.je.DatabaseException;
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import com.sleepycat.je.Database;
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import com.sleepycat.je.DatabaseConfig;
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...
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// Environment open omitted for brevity
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...
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Database myDatabase = null;
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try {
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DatabaseConfig dbConfig = new DatabaseConfig();
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dbConfig.setAllowCreate(true);
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dbConfig.setSortedDuplicates(true);
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myDatabase =
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myDbEnv.openDatabase(null,
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"sampleDatabase",
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dbConfig);
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} catch (DatabaseException dbe) {
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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="databases.html">Prev</a> </td>
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<td width="20%" align="center">
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<a accesskey="u" href="databases.html">Up</a>
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</td>
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<td width="40%" align="right"> <a accesskey="n" href="DBAdmin.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 7. Databases </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"> Administrative Methods</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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