<?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>DB_ENV->set_lk_partitions()</title> <link rel="stylesheet" href="apiReference.css" type="text/css" /> <meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /> <link rel="start" href="index.html" title="Berkeley DB C API Reference" /> <link rel="up" href="lock.html" title="Chapter 6. The DB_LOCK Handle" /> <link rel="prev" href="envset_lk_max_objects.html" title="DB_ENV->set_lk_max_objects()" /> <link rel="next" href="lockdetect.html" title="DB_ENV->lock_detect()" /> </head> <body> <div class="navheader"> <table width="100%" summary="Navigation header"> <tr> <th colspan="3" align="center">DB_ENV->set_lk_partitions()</th> </tr> <tr> <td width="20%" align="left"><a accesskey="p" href="envset_lk_max_objects.html">Prev</a> </td> <th width="60%" align="center">Chapter 6. The DB_LOCK Handle </th> <td width="20%" align="right"> <a accesskey="n" href="lockdetect.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="envset_lk_partitions"></a>DB_ENV->set_lk_partitions()</h2> </div> </div> </div> <pre class="programlisting">#include <db.h> int DB_ENV->set_lk_partitions(DB_ENV *dbenv, u_int32_t partitions); </pre> <p> Set the number of lock table partitions in the Berkeley DB environment. The default value is 10 times the number of CPUs on the system if there is more than one CPU. Increasing the number of partitions can provide for greater throughput on a system with multiple CPUs and more than one thread contending for the lock manager. On single processor systems more than one partition may increase the overhead of the lock manager. Systems often report threading contexts as CPUs. If your system does this, set the number of partitions to 1 to get optimal performance. </p> <p> The database environment's number of partitions may also be configured using the environment's <a href="../../programmer_reference/env_db_config.html#env_db_config.DB_CONFIG" class="olink">DB_CONFIG</a> file. The syntax of the entry in that file is a single line with the string "set_lk_partitions", one or more whitespace characters, and the number of partitions. Because the <a href="../../programmer_reference/env_db_config.html#env_db_config.DB_CONFIG" class="olink">DB_CONFIG</a> file is read when the database environment is opened, it will silently overrule configuration done before that time. </p> <p> The <code class="methodname">DB_ENV->set_lk_partitions()</code> method configures a database environment, not only operations performed using the specified <a class="link" href="env.html" title="Chapter 5. The DB_ENV Handle">DB_ENV</a> handle. </p> <p> The <code class="methodname">DB_ENV->set_lk_partitions()</code> method may not be called after the <a class="xref" href="envopen.html" title="DB_ENV->open()">DB_ENV->open()</a> method is called. If the database environment already exists when <a class="xref" href="envopen.html" title="DB_ENV->open()">DB_ENV->open()</a> is called, the information specified to <code class="methodname">DB_ENV->set_lk_partitions()</code> will be ignored. </p> <p> The <code class="methodname">DB_ENV->set_lk_partitions()</code> <span> <span> method returns a non-zero error value on failure and 0 on success. </span> </span> </p> <div class="sect2" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h3 class="title"><a id="id1676467"></a>Parameters</h3> </div> </div> </div> <div class="sect3" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h4 class="title"><a id="id1676584"></a>partitions</h4> </div> </div> </div> <p> The <span class="bold"><strong>partitions</strong></span> parameter is the number of partitions to be configured in the Berkeley DB environment. </p> </div> </div> <div class="sect2" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h3 class="title"><a id="id1676468"></a>Errors</h3> </div> </div> </div> <p> The <code class="methodname">DB_ENV->set_lk_partitions()</code> <span> <span> method may fail and return one of the following non-zero errors: </span> </span> </p> <div class="sect3" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h4 class="title"><a id="id1676519"></a>EINVAL</h4> </div> </div> </div> <p> If the method was called after <a class="xref" href="envopen.html" title="DB_ENV->open()">DB_ENV->open()</a> was called; or if an invalid flag value or parameter was specified. </p> </div> </div> <div class="sect2" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h3 class="title"><a id="id1676659"></a>Class</h3> </div> </div> </div> <p> <a class="link" href="env.html" title="Chapter 5. The DB_ENV Handle">DB_ENV</a>, <a class="link" href="lock.html" title="Chapter 6. The DB_LOCK Handle">DB_LOCK</a> </p> </div> <div class="sect2" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h3 class="title"><a id="id1676632"></a>See Also</h3> </div> </div> </div> <p> <a class="xref" href="lock.html#locklist" title="Locking Subsystem and Related Methods">Locking Subsystem and Related Methods</a> </p> </div> </div> <div class="navfooter"> <hr /> <table width="100%" summary="Navigation footer"> <tr> <td width="40%" align="left"><a accesskey="p" href="envset_lk_max_objects.html">Prev</a> </td> <td width="20%" align="center"> <a accesskey="u" href="lock.html">Up</a> </td> <td width="40%" align="right"> <a accesskey="n" href="lockdetect.html">Next</a></td> </tr> <tr> <td width="40%" align="left" valign="top">DB_ENV->set_lk_max_objects() </td> <td width="20%" align="center"> <a accesskey="h" href="index.html">Home</a> </td> <td width="40%" align="right" valign="top"> DB_ENV->lock_detect()</td> </tr> </table> </div> </body> </html>