mirror of
https://github.com/yasuhirokimura/db18
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Yasuhiro KIMURA
124 lines
5.7 KiB
HTML
124 lines
5.7 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>New Replication Manager Flags</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 Installation and Build Guide" />
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<link rel="up" href="upgrade_181_toc.html" title="Chapter 8. Upgrading Berkeley DB 12.1.6.2 applications to Berkeley DB 18.1" />
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<link rel="prev" href="new_rep_objects.html" title="New Replication Environment Region Objects" />
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<link rel="next" href="new_information.html" title="New Information Available to Replicated Applications" />
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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">New Replication Manager Flags</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="new_rep_objects.html">Prev</a> </td>
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<th width="60%" align="center">Chapter 8. Upgrading Berkeley DB 12.1.6.2 applications to
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Berkeley DB 18.1 </th>
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<td width="20%" align="right"> <a accesskey="n" href="new_information.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="new_flags"></a>New Replication Manager Flags</h2>
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</div>
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</div>
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</div>
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<div class="toc">
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<dl>
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<dt>
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<span class="sect2">
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<a href="new_flags.html#idm140649573050000">New Parameter Values</a>
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</span>
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</dt>
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</dl>
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</div>
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<p>
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Prior to the 18.1 release, Berkeley DB's replication manager managed connections
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using the <code class="literal">select()</code> call which has a limitation of 1024 open
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file descriptors. Application working with a very large number of databases, files
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or network connections and thus consuming more than 1024 file descriptors, were
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likely to run into this limitation.
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</p>
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<p>
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Berkeley DB's 18.1 release offers the use of <code class="literal">poll()</code>
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and/or <code class="literal">epoll()</code> in preference to <code class="literal">select()</code>.
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In the new implementation, <code class="literal">poll()</code> is preferred over
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<code class="literal">select()</code> because it does not limit the number of open file
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descriptors. If <code class="literal">epoll()</code> is available and the number of
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open file descriptors is greater than 1024, <code class="literal">epoll()</code> is
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preferred over <code class="literal">poll()</code> because it scales better.
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</p>
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<p>
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No changes are necessary to use the new defaults, but new flags have been added
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for the user to disable <code class="literal">poll()</code> and <code class="literal">epoll()</code> and
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fall back to <code class="literal">select()</code>.
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</p>
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<div class="sect2" 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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<h3 class="title"><a id="idm140649573050000"></a>New Parameter Values</h3>
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</div>
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</div>
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</div>
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<div class="itemizedlist">
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<ul type="disc">
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<li>
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<code class="literal">DB_REPMGR_CONF_DISABLE_POLL</code>
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<p>
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A new <code class="literal">flags</code> parameter value for the
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<code class="literal">DB_ENV->rep_set_config()</code>
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method to indicate that <code class="literal">poll()</code> should not be used.
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</p>
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</li>
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<li>
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<code class="literal">DB_REPMGR_CONF_DISABLE_EPOLL</code>
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<p>
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A new <code class="literal">flags</code> parameter value for the
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<code class="literal">DB_ENV->rep_set_config()</code> method to
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indicate that <code class="literal">epoll()</code> should be used (if supported
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by the target OS). Note that this flag needs to be explicitly
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specified for <code class="literal">epoll()</code> to be used by the replication
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subsystem.
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</p>
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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>
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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="new_rep_objects.html">Prev</a> </td>
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<td width="20%" align="center">
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<a accesskey="u" href="upgrade_181_toc.html">Up</a>
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</td>
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<td width="40%" align="right"> <a accesskey="n" href="new_information.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">New Replication Environment Region Objects </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"> New Information Available to Replicated Applications</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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