<!--$Id: memp_set_priority.so,v 10.25 2007/05/22 18:06:06 bostic Exp $--> <!--Copyright (c) 1997,2007 Oracle. All rights reserved.--> <!--See the file LICENSE for redistribution information.--> <html> <head> <title>Berkeley DB: DbMpoolFile::set_priority</title> <meta name="description" content="Berkeley DB: An embedded database programmatic toolkit."> <meta name="keywords" content="embedded,database,programmatic,toolkit,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,Java,C,C++"> </head> <body bgcolor=white> <table width="100%"><tr valign=top> <td> <h3>DbMpoolFile::set_priority</h3> </td> <td align=right> <a href="../../db46-devel-4.6.21/api_cxx/api_core.html"><img src="../../db46-devel-4.6.21/images/api.gif" alt="API"></a> <a href="../../db46-devel-4.6.21/ref/toc.html"><img src="../../db46-devel-4.6.21/images/ref.gif" alt="Ref"></a></td> </tr></table> <hr size=1 noshade> <tt> <h3><pre> #include <db_cxx.h> <p> int DbMpoolFile::set_priority(DB_CACHE_PRIORITY priority); <p> int DbMpoolFile::get_priority(DB_CACHE_PRIORITY *priorityp); </pre></h3> <hr size=1 noshade> <h3>Description: DbMpoolFile::set_priority</h3> <!--$Id: dbc_set_priority.so,v 1.3 2007/05/22 18:06:05 bostic Exp $--> <p>Set the cache priority for pages referenced by the <a href="../../db46-devel-4.6.21/api_cxx/mempfile_class.html">DbMpoolFile</a> handle.</p> <p>The priority of a page biases the replacement algorithm to be more or less likely to discard a page when space is needed in the buffer pool. The bias is temporary, and pages will eventually be discarded if they are not referenced again. The DbMpoolFile::set_priority method is only advisory, and does not guarantee pages will be treated in a specific way.</p> <p>To set the priority for the pages belonging to a particular database, call the DbMpoolFile::set_priority method using the <a href="../../db46-devel-4.6.21/api_cxx/mempfile_class.html">DbMpoolFile</a> handle returned by the <a href="../../db46-devel-4.6.21/api_cxx/db_get_mpf.html">Db::get_mpf</a> method.</p> <p>The DbMpoolFile::set_priority method configures a file in the memory pool, not only operations performed using the specified <a href="../../db46-devel-4.6.21/api_cxx/mempfile_class.html">DbMpoolFile</a> handle.</p> <p>The DbMpoolFile::set_priority method may be called at any time during the life of the application.</p> <p>The DbMpoolFile::set_priority 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> <h3>Parameters</h3> <dl compact> <dt><b>priority</b><dd>The <b>priority</b> parameter must be set to one of the following values: <dl compact> <dt><a name="DB_PRIORITY_VERY_LOW">DB_PRIORITY_VERY_LOW</a><dd>The lowest priority: pages are the most likely to be discarded. <dt><a name="DB_PRIORITY_LOW">DB_PRIORITY_LOW</a><dd>The next lowest priority. <dt><a name="DB_PRIORITY_DEFAULT">DB_PRIORITY_DEFAULT</a><dd>The default priority. <dt><a name="DB_PRIORITY_HIGH">DB_PRIORITY_HIGH</a><dd>The next highest priority. <dt><a name="DB_PRIORITY_VERY_HIGH">DB_PRIORITY_VERY_HIGH</a><dd>The highest priority: pages are the least likely to be discarded. </dl> </dl> <hr size=1 noshade> <h3>Description: DbMpoolFile::get_priority</h3> <p>The DbMpoolFile::get_priority method returns the cache priority for the file referenced by the <a href="../../db46-devel-4.6.21/api_cxx/mempfile_class.html">DbMpoolFile</a> handle.</p> <p>The DbMpoolFile::get_priority method may be called at any time during the life of the application.</p> <p>The DbMpoolFile::get_priority method either returns a non-zero error value or throws an exception that encapsulates a non-zero error value on failure <hr size=1 noshade> <h3>Class</h3> <a href="../../db46-devel-4.6.21/api_cxx/env_class.html">DbEnv</a>, <a href="../../db46-devel-4.6.21/api_cxx/mempfile_class.html">DbMpoolFile</a> <h3>See Also</h3> <a href="../../db46-devel-4.6.21/api_cxx/memp_list.html">Memory Pools and Related Methods</a> </tt> <table width="100%"><tr><td><br></td><td align=right> <a href="../../db46-devel-4.6.21/api_cxx/api_core.html"><img src="../../db46-devel-4.6.21/images/api.gif" alt="API"></a><a href="../../db46-devel-4.6.21/ref/toc.html"><img src="../../db46-devel-4.6.21/images/ref.gif" alt="Ref"></a> </td></tr></table> <p><font size=1>Copyright (c) 1996,2007 Oracle. All rights reserved.</font> </body> </html>