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94 lines
4.2 KiB
HTML
94 lines
4.2 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 11.2.5.3</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.
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Access Method Operations
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</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>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.</p>
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<p>There is one flag that you can set to customize <a href="../api_reference/C/dbclose.html" class="olink">DB->close()</a>:</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>Do not flush cached information to disk.</dd>
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</dl>
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</div>
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<span class="bold">
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<strong>It is important to understand that flushing cached information
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to disk only minimizes the window of opportunity for corrupted data, it
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does not eliminate the possibility.</strong>
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</span>
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<p>While unlikely, it is possible for database corruption to happen if a
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system or application crash occurs while writing data to the database. To
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ensure that database corruption never occurs, applications must either:</p>
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<div class="itemizedlist">
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<ul type="disc">
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<li>Use transactions and logging with automatic recovery.</li>
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<li>Use logging and application-specific recovery.</li>
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<li>Edit a copy of the database, and, once all applications
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using the database have successfully called <a href="../api_reference/C/dbclose.html" class="olink">DB->close()</a>, use
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system operations (for example, the POSIX rename system call) to
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atomically replace the original database with the updated copy.</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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