176 lines
7.0 KiB
HTML
176 lines
7.0 KiB
HTML
<?xml version="1.0" encoding="ISO-8859-1" 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=ISO-8859-1" />
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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 V1.62.4" />
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<link rel="home" href="index.html" title="Getting Started with Berkeley DB" />
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<link rel="up" href="DB.html" title="Chapter 2. Databases" />
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<link rel="previous" href="coredbclose.html" title="Closing 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 class="navheader">
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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="coredbclose.html">Prev</a> </td>
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<th width="60%" align="center">Chapter 2. 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="db_config"></a>Database Properties</h2>
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</div>
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</div>
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<div></div>
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</div>
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<p>You can set database properties using the <tt class="classname">DatabaseConfig</tt>
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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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<tt class="classname">DatabaseConfig</tt> object used by your database using
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the <tt class="methodname">Database.getConfig()</tt> method.</p>
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<p>
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There are a large number of properties that you can set using this
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class (see the javadoc for a complete listing). From the perspective of
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this manual, some of the more interesting properties are:
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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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<tt class="methodname">DatabaseConfig.setAllowCreate()</tt>
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</p>
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<p>If <tt class="literal">true</tt>, 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 <tt class="literal">false</tt>.</p>
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</li>
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<li>
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<p>
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<tt class="methodname">DatabaseConfig.setBtreeComparator()</tt>
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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. For more information, see
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<span><a href="btree.html#comparators">Setting Comparison Functions</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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<tt class="methodname">DatabaseConfig.setDuplicateComparator()</tt>
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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 href="btree.html#comparators">Setting Comparison Functions</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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<tt class="methodname">DatabaseConfig.setSortedDuplicates()</tt>
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</p>
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<p>If <tt class="literal">true</tt>, duplicate records are allowed in the
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database. If this value is <tt class="literal">false</tt>, then putting a duplicate record into the database
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results in the replacement of the old record with the new record.
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Note that this property can be set only at database creation time. Default is <tt class="literal">false</tt>.
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</p>
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</li>
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<li>
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<p>
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<tt class="methodname">DatabaseConfig.setExclusiveCreate()</tt>
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</p>
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<p>If <tt class="literal">true</tt>, 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 <tt class="literal">false</tt>.</p>
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</li>
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<li>
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<p>
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<tt class="methodname">DatabaseConfig.setReadOnly()</tt>
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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 <tt class="literal">false</tt>.</p>
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</li>
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<li>
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<p>
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<tt class="methodname">DatabaseConfig.setTruncate()</tt>
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</p>
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<p>If true, the database is truncated; that is, it is emptied of all
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content.
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</p>
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</li>
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<li>
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<p>
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<tt class="methodname">DatabaseConfig.setType()</tt>
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</p>
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<p>Identifies the type of database that you want to create. This
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manual will exclusively use <tt class="literal">DatabaseType.BTREE</tt>.
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</p>
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</li>
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</ul>
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</div>
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<p>
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In addition to these, there are also methods that allow you to
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control the IO stream used for error reporting purposes.
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These are described later in this manual.
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</p>
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<p>For example:</p>
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<a id="java_db3"></a>
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<pre class="programlisting">package com.sleepycat.examples.db.GettingStarted;
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import com.sleepycat.db.Database;
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import com.sleepycat.db.DatabaseConfig;
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import com.sleepycat.db.DatabaseException;
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import com.sleepycat.db.DatabaseType;
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import java.io.FileNotFoundException;
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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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dbConfig.setType(DatabaseType.BTREE);
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myDatabase = new Database("sampleDatabase.db",
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null,
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dbConfig);
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} catch (DatabaseException dbe) {
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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>
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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="coredbclose.html">Prev</a> </td>
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||
<td width="20%" align="center">
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<a accesskey="u" href="DB.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">Closing 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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