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<h2 class="title" style="clear: both"><a id="envset_lk_partitions"></a>DbEnv::set_lk_partitions()</h2>
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<pre class="programlisting">#include <db_cxx.h>
int
DbEnv::set_lk_partitions(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">DbEnv::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 DbEnv Handle">DbEnv</a> handle.
</p>
<p>
The <code class="methodname">DbEnv::set_lk_partitions()</code> method may not be called after the
<a class="xref" href="envopen.html" title="DbEnv::open()">DbEnv::open()</a> method is
called. If the database environment already exists when
<a class="xref" href="envopen.html" title="DbEnv::open()">DbEnv::open()</a> is called, the
information specified to <code class="methodname">DbEnv::set_lk_partitions()</code> will be ignored.
</p>
<p>
The <code class="methodname">DbEnv::set_lk_partitions()</code> <span>
<span>
method either returns a non-zero error value or throws an
exception that encapsulates a non-zero error value on
failure, and returns 0 on success.
</span>
</span>
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<h3 class="title"><a id="id1680949"></a>Parameters</h3>
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<div>
<h4 class="title"><a id="id1680957"></a>partitions</h4>
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<p>
The <span class="bold"><strong>partitions</strong></span> parameter is the
number of partitions to be configured in the Berkeley DB environment.
</p>
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<h3 class="title"><a id="id1681115"></a>Errors</h3>
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<p>
The <code class="methodname">DbEnv::set_lk_partitions()</code> <span>
<span>
method may fail and throw a <a class="link" href="dbexception.html" title="Chapter 6. The DbException Class">DbException</a>
exception, encapsulating one of the following non-zero errors, or 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="id1681130"></a>EINVAL</h4>
</div>
</div>
</div>
<p>
If the method was called after <a class="xref" href="envopen.html" title="DbEnv::open()">DbEnv::open()</a>
was called; or if an invalid flag value or parameter was specified.
</p>
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<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
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<h3 class="title"><a id="id1681131"></a>Class</h3>
</div>
</div>
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<p>
<a class="link" href="env.html" title="Chapter 5. The DbEnv Handle">DbEnv</a>,
<a class="link" href="lock.html" title="Chapter 7. The DbLock Handle">DbLock</a>
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<h3 class="title"><a id="id1680888"></a>See Also</h3>
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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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