mirror of
https://github.com/yasuhirokimura/db18
synced 2026-06-08 18:29:23 +00:00
Yasuhiro KIMURA
116 lines
4.5 KiB
HTML
116 lines
4.5 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 close</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="Berkeley DB Programmer's Reference Guide" />
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<link rel="up" href="am.html" title="Chapter 3. Access Method Operations" />
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<link rel="prev" href="am_sync.html" title="Flushing the database cache" />
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<link rel="next" href="am_second.html" title="Secondary indexes" />
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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 18.1.40</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 close</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="am_sync.html">Prev</a> </td>
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<th width="60%" align="center">Chapter 3. Access Method Operations </th>
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<td width="20%" align="right"> <a accesskey="n" href="am_second.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="am_close"></a>Database close</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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The <a href="../api_reference/C/dbclose.html" class="olink">DB->close()</a> database handle closes the <a href="../api_reference/C/db.html" class="olink">DB</a> handle. By
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default, <a href="../api_reference/C/dbclose.html" class="olink">DB->close()</a> also flushes all modified records from the
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database cache to disk.
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</p>
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<p>
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There is one flag that you can set to customize
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<a href="../api_reference/C/dbclose.html" class="olink">DB->close()</a>:
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</p>
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<div class="variablelist">
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<dl>
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<dt>
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<span class="term">
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<a href="../api_reference/C/dbclose.html#dbclose_DB_NOSYNC" class="olink">DB_NOSYNC</a>
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</span>
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</dt>
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<dd>
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Do not flush cached information to
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disk.
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</dd>
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</dl>
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</div>
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<span class="bold">
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<strong>
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It is important to understand that flushing
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cached information to disk only minimizes the window of
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opportunity for corrupted data, it does not eliminate the
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possibility.
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</strong>
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</span>
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<p>
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While unlikely, it is possible for database corruption to
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happen if a system or application crash occurs while writing
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data to the database. To ensure that database corruption never
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occurs, applications must either:
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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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Use transactions and logging with automatic
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recovery.
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</li>
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<li>
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Use logging and application-specific
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recovery.
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</li>
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<li>
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Edit a copy of the database, and, once all
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applications using the database have successfully called
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<a href="../api_reference/C/dbclose.html" class="olink">DB->close()</a>, use system operations (for example, the POSIX
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rename system call) to atomically replace the original
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database with the updated copy.
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</li>
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</ul>
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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="am_sync.html">Prev</a> </td>
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<td width="20%" align="center">
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<a accesskey="u" href="am.html">Up</a>
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</td>
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<td width="40%" align="right"> <a accesskey="n" href="am_second.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">Flushing the database cache </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"> Secondary indexes</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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