2011-09-13 17:44:24 +00:00
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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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<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
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<title>Flushing the database cache</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_verify.html" title="Database verification and salvage" />
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<link rel="next" href="am_close.html" title="Database close" />
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</head>
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<body>
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<div class="libver">
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2012-11-14 21:35:20 +00:00
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<p>Library Version 11.2.5.3</p>
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2011-09-13 17:44:24 +00:00
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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">Flushing the database cache</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_verify.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_close.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_sync"></a>Flushing the database cache</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/dbsync.html" class="olink">DB->sync()</a> method flushes all modified records from the database
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cache to disk.</p>
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<p>
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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>
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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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<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_verify.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_close.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">Database verification and salvage </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"> Database close</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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