mirror of
https://github.com/yasuhirokimura/db18
synced 2026-06-08 18:29:23 +00:00
Yasuhiro KIMURA
97 lines
3.8 KiB
HTML
97 lines
3.8 KiB
HTML
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||
<head>
|
||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||
<title>Flushing the database cache</title>
|
||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||
<link rel="start" href="index.html" title="Berkeley DB Programmer's Reference Guide" />
|
||
<link rel="up" href="am.html" title="Chapter 3. Access Method Operations" />
|
||
<link rel="prev" href="am_verify.html" title="Database verification and salvage" />
|
||
<link rel="next" href="am_close.html" title="Database close" />
|
||
</head>
|
||
<body>
|
||
<div xmlns="" class="navheader">
|
||
<div class="libver">
|
||
<p>Library Version 18.1.40</p>
|
||
</div>
|
||
<table width="100%" summary="Navigation header">
|
||
<tr>
|
||
<th colspan="3" align="center">Flushing the database cache</th>
|
||
</tr>
|
||
<tr>
|
||
<td width="20%" align="left"><a accesskey="p" href="am_verify.html">Prev</a> </td>
|
||
<th width="60%" align="center">Chapter 3. Access Method Operations </th>
|
||
<td width="20%" align="right"> <a accesskey="n" href="am_close.html">Next</a></td>
|
||
</tr>
|
||
</table>
|
||
<hr />
|
||
</div>
|
||
<div class="sect1" lang="en" xml:lang="en">
|
||
<div class="titlepage">
|
||
<div>
|
||
<div>
|
||
<h2 class="title" style="clear: both"><a id="am_sync"></a>Flushing the database cache</h2>
|
||
</div>
|
||
</div>
|
||
</div>
|
||
<p>
|
||
The <a href="../api_reference/C/dbsync.html" class="olink">DB->sync()</a> method flushes all modified records from the
|
||
database cache to disk.
|
||
</p>
|
||
<p>
|
||
<span class="bold"><strong>It is important to understand that
|
||
flushing cached information to disk only minimizes the
|
||
window of opportunity for corrupted data, it does not
|
||
eliminate the possibility.</strong></span>
|
||
</p>
|
||
<p>
|
||
While unlikely, it is possible for database corruption to
|
||
happen if a system or application crash occurs while writing
|
||
data to the database. To ensure that database corruption never
|
||
occurs, applications must either:
|
||
</p>
|
||
<div class="itemizedlist">
|
||
<ul type="disc">
|
||
<li>
|
||
Use transactions and logging with automatic
|
||
recovery.
|
||
</li>
|
||
<li>
|
||
Use logging and application-specific
|
||
recovery.
|
||
</li>
|
||
<li>
|
||
Edit a copy of the database, and, once all
|
||
applications using the database have successfully called
|
||
<a href="../api_reference/C/dbclose.html" class="olink">DB->close()</a>, use system operations (for example, the POSIX
|
||
rename system call) to atomically replace the original
|
||
database with the updated copy.
|
||
</li>
|
||
</ul>
|
||
</div>
|
||
</div>
|
||
<div class="navfooter">
|
||
<hr />
|
||
<table width="100%" summary="Navigation footer">
|
||
<tr>
|
||
<td width="40%" align="left"><a accesskey="p" href="am_verify.html">Prev</a> </td>
|
||
<td width="20%" align="center">
|
||
<a accesskey="u" href="am.html">Up</a>
|
||
</td>
|
||
<td width="40%" align="right"> <a accesskey="n" href="am_close.html">Next</a></td>
|
||
</tr>
|
||
<tr>
|
||
<td width="40%" align="left" valign="top">Database verification and
|
||
salvage </td>
|
||
<td width="20%" align="center">
|
||
<a accesskey="h" href="index.html">Home</a>
|
||
</td>
|
||
<td width="40%" align="right" valign="top"> Database close</td>
|
||
</tr>
|
||
</table>
|
||
</div>
|
||
</body>
|
||
</html>
|