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183 lines
7.7 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>DB_ENV->set_lk_partitions()</title>
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<link rel="stylesheet" href="apiReference.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 C API Reference" />
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<link rel="up" href="lock.html" title="Chapter 6. The DB_LOCK Handle" />
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<link rel="prev" href="envset_lk_max_objects.html" title="DB_ENV->set_lk_max_objects()" />
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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">DB_ENV->set_lk_partitions()</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="envset_lk_max_objects.html">Prev</a> </td>
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<th width="60%" align="center">Chapter 6.
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The DB_LOCK Handle
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</th>
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<td width="20%" align="right"> <a accesskey="n" href="envset_lk_priority.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="envset_lk_partitions"></a>DB_ENV->set_lk_partitions()</h2>
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</div>
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</div>
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</div>
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<pre class="programlisting">#include <db.h>
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int
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DB_ENV->set_lk_partitions(DB_ENV *dbenv, u_int32_t partitions); </pre>
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<p>
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Set the number of lock table partitions in the Berkeley DB
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environment. The default value is 10 times the number of CPUs on the
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system if there is more than one CPU. Increasing the number of
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partitions can provide for greater throughput on a system with
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multiple CPUs and more than one thread contending for the lock
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manager. On single processor systems more than one partition may
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increase the overhead of the lock manager. Systems often report
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threading contexts as CPUs. If your system does this, set the number of
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partitions to 1 to get optimal performance.
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</p>
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<p>
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The database environment's number of partitions may also be configured
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using the environment's <a href="../../programmer_reference/env_db_config.html#env_db_config.DB_CONFIG" class="olink">DB_CONFIG</a> file. The
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syntax of the entry in that file is a single line with the string
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"set_lk_partitions", one or more whitespace characters, and the number
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of partitions. Because the <a href="../../programmer_reference/env_db_config.html#env_db_config.DB_CONFIG" class="olink">DB_CONFIG</a> file is
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read when the database environment is opened, it will silently
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overrule configuration done before that time.
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</p>
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<p>
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The <code class="methodname">DB_ENV->set_lk_partitions()</code> method configures a database
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environment, not only operations performed using the specified
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<a class="link" href="env.html" title="Chapter 5. The DB_ENV Handle">DB_ENV</a> handle.
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</p>
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<p>
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The <code class="methodname">DB_ENV->set_lk_partitions()</code> method may not be called after the
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<a class="xref" href="envopen.html" title="DB_ENV->open()">DB_ENV->open()</a> method is
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called. If the database environment already exists when
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<a class="xref" href="envopen.html" title="DB_ENV->open()">DB_ENV->open()</a> is called, the
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information specified to <code class="methodname">DB_ENV->set_lk_partitions()</code> will be ignored.
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</p>
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<p>
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The <code class="methodname">DB_ENV->set_lk_partitions()</code> <span>
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<span>
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method returns a non-zero error value on failure and 0 on success.
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</span>
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</span>
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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="idp60512144"></a>Parameters</h3>
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</div>
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</div>
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</div>
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<div class="sect3" 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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<h4 class="title"><a id="idp60514616"></a>partitions</h4>
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</div>
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</div>
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</div>
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<p>
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The <span class="bold"><strong>partitions</strong></span> parameter is the
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number of partitions to be configured in the Berkeley DB environment.
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</p>
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</div>
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</div>
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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="idp60466088"></a>Errors</h3>
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</div>
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</div>
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</div>
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<p>
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The <code class="methodname">DB_ENV->set_lk_partitions()</code> <span>
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<span>
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method may fail and return one of the following non-zero errors:
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</span>
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</span>
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</p>
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<div class="sect3" 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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<h4 class="title"><a id="idp60536624"></a>EINVAL</h4>
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</div>
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</div>
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</div>
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<p>
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If the method was called after <a class="xref" href="envopen.html" title="DB_ENV->open()">DB_ENV->open()</a>
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was called; or if an invalid flag value or parameter was specified.
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</p>
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</div>
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</div>
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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="idp60514680"></a>Class</h3>
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</div>
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</div>
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</div>
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<p>
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<a class="link" href="env.html" title="Chapter 5. The DB_ENV Handle">DB_ENV</a>,
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<a class="link" href="lock.html" title="Chapter 6. The DB_LOCK Handle">DB_LOCK</a>
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</p>
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</div>
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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="idp60538792"></a>See Also</h3>
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</div>
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</div>
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</div>
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<p>
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<a class="xref" href="lock.html#locklist" title="Locking Subsystem and Related Methods">Locking Subsystem and Related Methods</a>
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</p>
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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="envset_lk_max_objects.html">Prev</a> </td>
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<td width="20%" align="center">
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<a accesskey="u" href="lock.html">Up</a>
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</td>
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<td width="40%" align="right"> <a accesskey="n" href="envset_lk_priority.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">DB_ENV->set_lk_max_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"> DB_ENV->set_lk_priority()</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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