mirror of
https://github.com/yasuhirokimura/db18
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Yasuhiro KIMURA
111 lines
4.5 KiB
HTML
111 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>Log file limits</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="log.html" title="Chapter 18. The Logging Subsystem" />
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<link rel="prev" href="log_config.html" title="Configuring logging" />
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<link rel="next" href="mp.html" title="Chapter 19. The Memory Pool Subsystem" />
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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">Log file limits</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="log_config.html">Prev</a> </td>
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<th width="60%" align="center">Chapter 18. The Logging Subsystem </th>
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<td width="20%" align="right"> <a accesskey="n" href="mp.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="log_limits"></a>Log file limits</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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Log filenames and sizes impose a limit on how long databases
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may be used in a Berkeley DB database environment. It is quite
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unlikely that an application will reach this limit; however,
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if the limit is reached, the Berkeley DB environment's
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databases must be dumped and reloaded.
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</p>
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<p>
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The log filename consists of <span class="bold"><strong>log.</strong></span>
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followed by 10 digits, with a maximum of
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2,000,000,000 log files. Consider an application performing
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6000 transactions per second for 24 hours a day, logged into
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10MB log files, in which each transaction is logging
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approximately 500 bytes of data. The following
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calculation:
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</p>
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<pre class="programlisting">(10 * 2^20 * 2000000000) / (6000 * 500 * 365 * 60 * 60 * 24) = ~221</pre>
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<p>
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indicates that the system will run out of log filenames in
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roughly 221 years.
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</p>
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<p>
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There is no way to reset the log filename space in Berkeley
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DB. If your application is reaching the end of its log
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filename space, you must do the following:
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</p>
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<div class="orderedlist">
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<ol type="1">
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<li>
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Archive your databases as if to prepare for
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catastrophic failure (see <a class="xref" href="transapp_archival.html" title="Database and log file archival">Database and log file
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archival</a> for more
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information).
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</li>
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<li>
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Reset the database's log sequence numbers (see the
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<span class="bold"><strong>-r</strong></span> option to the
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<a href="../api_reference/C/db_load.html" class="olink">db_load</a> utility for more information).
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</li>
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<li>
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Remove all of the log files from the database
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environment. (This is the only situation in which all the
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log files are removed from an environment; in all other
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cases, at least a single log file is retained.)
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</li>
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<li>
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Restart your application.
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</li>
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</ol>
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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="log_config.html">Prev</a> </td>
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<td width="20%" align="center">
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<a accesskey="u" href="log.html">Up</a>
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</td>
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<td width="40%" align="right"> <a accesskey="n" href="mp.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">Configuring logging </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"> Chapter 19. The Memory Pool Subsystem </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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