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<!--$Id: mempfile_class.so,v 10.24 2004/08/13 03:38:58 bostic Exp $-->
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<h3>DB_MPOOLFILE</h3>
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<h3><pre>
#include <db.h>
<p>
typedef struct __db_mpoolfile DB_MPOOLFILE;
</pre></h3>
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<h3>Description: DB_MPOOLFILE</h3>
<p>The memory pool interfaces for the Berkeley DB database environment are
methods of the <a href="../api_c/env_class.html">DB_ENV</a> handle. The <a href="../api_c/env_class.html">DB_ENV</a> memory pool
methods and the DB_MPOOLFILE class provide general-purpose,
page-oriented buffer management of files. Although designed to work
with the other <a href="../api_c/db_class.html">DB</a> classes, they are also useful for more general
purposes. The memory pools are referred to in this document as simply
<i>pools</i>.</p>
<p>Pools may be shared between processes. Pools are usually filled by
pages from one or more files. Pages in the pool are replaced in LRU
(least-recently-used) order, with each new page replacing the page that
has been unused the longest. Pages retrieved from the pool using
<a href="../api_c/memp_fget.html">DB_MPOOLFILE->get</a> are <i>pinned</i> in the pool until they are
returned to the control of the buffer pool using the <a href="../api_c/memp_fput.html">DB_MPOOLFILE->put</a>
method.</p>
<p>The DB_MPOOLFILE object is the handle for a file in the memory
pool. The handle is not free-threaded. Once the <a href="../api_c/memp_fclose.html">DB_MPOOLFILE->close</a> method
is called, the handle may not be accessed again, regardless of that
method's return.</p>
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<h3>Class</h3>
<a href="../api_c/env_class.html">DB_ENV</a>, DB_MPOOLFILE
<h3>See Also</h3>
<a href="../api_c/memp_list.html">Memory Pools and Related Methods</a>
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