103 lines
4.5 KiB
HTML
103 lines
4.5 KiB
HTML
<!--$Id: env_set_lk_partitions.html 63573 2008-05-23 21:43:21Z trent.nelson $-->
|
|
<!--Copyright (c) 1997,2008 Oracle. All rights reserved.-->
|
|
<!--See the file LICENSE for redistribution information.-->
|
|
<html>
|
|
<head>
|
|
<title>Berkeley DB: DbEnv::set_lk_partitions</title>
|
|
<meta name="description" content="Berkeley DB: An embedded database programmatic toolkit.">
|
|
<meta name="keywords" content="embedded,database,programmatic,toolkit,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,Java,C,C++">
|
|
</head>
|
|
<body bgcolor=white>
|
|
<table width="100%"><tr valign=top>
|
|
<td>
|
|
<b>DbEnv::set_lk_partitions</b>
|
|
</td>
|
|
<td align=right>
|
|
<a href="../api_cxx/api_core.html"><img src="../images/api.gif" alt="API"></a>
|
|
<a href="../ref/toc.html"><img src="../images/ref.gif" alt="Ref"></a></td>
|
|
</tr></table>
|
|
<hr size=1 noshade>
|
|
<tt>
|
|
<b><pre>
|
|
#include <db_cxx.h>
|
|
<p>
|
|
int
|
|
DbEnv::set_lk_partitions(u_int32_t partitions);
|
|
<p>
|
|
int
|
|
DbEnv::get_lk_partitions(u_int32_t *lk_partitions);
|
|
</pre></b>
|
|
<hr size=1 noshade>
|
|
<b>Description: DbEnv::set_lk_partitions</b>
|
|
<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 this
|
|
may require setting 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="../ref/env/db_config.html#DB_CONFIG">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="../ref/env/db_config.html#DB_CONFIG">DB_CONFIG</a> file is read when the database environment
|
|
is opened, it will silently overrule configuration done before that
|
|
time.</p>
|
|
<p>The DbEnv::set_lk_partitions method configures a database environment, not only operations
|
|
performed using the specified <a href="../api_cxx/env_class.html">DbEnv</a> handle.</p>
|
|
<p>The DbEnv::set_lk_partitions method may not be called after the <a href="../api_cxx/env_open.html">DbEnv::open</a> method is
|
|
called.
|
|
If the database environment already exists when
|
|
<a href="../api_cxx/env_open.html">DbEnv::open</a> is called, the information specified to DbEnv::set_lk_partitions
|
|
will be ignored.
|
|
</p>
|
|
<p>The DbEnv::set_lk_partitions 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.
|
|
</p>
|
|
<b>Parameters</b> <br>
|
|
<b>partitions</b><ul compact><li>The <b>partitions</b> parameter is the number of partitions
|
|
to be configured in the Berkeley DB environment.</ul>
|
|
<br>
|
|
<br><b>Errors</b>
|
|
<p>The DbEnv::set_lk_partitions method
|
|
may fail and throw
|
|
<a href="../api_cxx/except_class.html">DbException</a>,
|
|
encapsulating one of the following non-zero errors, or return one of
|
|
the following non-zero errors:</p>
|
|
<br>
|
|
<b>EINVAL</b><ul compact><li>If the method was called after <a href="../api_cxx/env_open.html">DbEnv::open</a> was called; or if an
|
|
invalid flag value or parameter was specified.</ul>
|
|
<br>
|
|
<hr size=1 noshade>
|
|
<b>Description: DbEnv::get_lk_partitions</b>
|
|
<p>The DbEnv::get_lk_partitions method returns the number of partitions.</p>
|
|
<p>The DbEnv::get_lk_partitions method may be called at any time during the life of the
|
|
application.</p>
|
|
<p>The DbEnv::get_lk_partitions 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.
|
|
</p>
|
|
<b>Parameters</b> <br>
|
|
<b>lk_partitions</b><ul compact><li>The DbEnv::get_lk_partitions method returns the
|
|
number of partitions in <b>lk_partitions</b>.</ul>
|
|
<br>
|
|
<hr size=1 noshade>
|
|
<br><b>Class</b>
|
|
<a href="../api_cxx/env_class.html">DbEnv</a>, <a href="../api_cxx/lock_class.html">DbLock</a>
|
|
<br><b>See Also</b>
|
|
<a href="../api_cxx/lock_list.html">Locking Subsystem and Related Methods</a>
|
|
</tt>
|
|
<table width="100%"><tr><td><br></td><td align=right>
|
|
<a href="../api_cxx/api_core.html"><img src="../images/api.gif" alt="API"></a><a href="../ref/toc.html"><img src="../images/ref.gif" alt="Ref"></a>
|
|
</td></tr></table>
|
|
<p><font size=1>Copyright (c) 1996,2008 Oracle. All rights reserved.</font>
|
|
</body>
|
|
</html>
|