58 lines
2.7 KiB
HTML
58 lines
2.7 KiB
HTML
<!--$Id: mempfile_class.html 63573 2008-05-23 21:43:21Z trent.nelson $-->
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<!--Copyright (c) 1997,2008 Oracle. All rights reserved.-->
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<!--See the file LICENSE for redistribution information.-->
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<html>
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<head>
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<title>Berkeley DB: DB_MPOOLFILE</title>
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<meta name="description" content="Berkeley DB: An embedded database programmatic toolkit.">
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<meta name="keywords" content="embedded,database,programmatic,toolkit,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,Java,C,C++">
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</head>
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<body bgcolor=white>
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<table width="100%"><tr valign=top>
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<td>
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<b>DB_MPOOLFILE</b>
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</td>
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<td align=right>
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<a href="../api_c/api_core.html"><img src="../images/api.gif" alt="API"></a>
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<a href="../ref/toc.html"><img src="../images/ref.gif" alt="Ref"></a></td>
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</tr></table>
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<hr size=1 noshade>
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<tt>
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<b><pre>
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#include <db.h>
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<p>
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typedef struct __db_mpoolfile DB_MPOOLFILE;
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</pre></b>
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<hr size=1 noshade>
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<b>Description: DB_MPOOLFILE</b>
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<p>The memory pool interfaces for the Berkeley DB database environment are
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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
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methods and the DB_MPOOLFILE class provide general-purpose,
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page-oriented buffer management of files. Although designed to work
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with the other <a href="../api_c/db_class.html">DB</a> classes, they are also useful for more general
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purposes. The memory pools are referred to in this document as simply
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<i>pools</i>.</p>
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<p>Pools may be shared between processes. Pools are usually filled by
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pages from one or more files. Pages in the pool are replaced in LRU
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(least-recently-used) order, with each new page replacing the page that
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has been unused the longest. Pages retrieved from the pool using
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<a href="../api_c/memp_fget.html">DB_MPOOLFILE->get</a> are <i>pinned</i> in the pool until they are
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returned to the control of the buffer pool using the <a href="../api_c/memp_fput.html">DB_MPOOLFILE->put</a>
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method.</p>
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<p>The DB_MPOOLFILE object is the handle for a file in the memory
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pool. The handle is not free-threaded. Once the <a href="../api_c/memp_fclose.html">DB_MPOOLFILE->close</a> method
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is called, the handle may not be accessed again, regardless of that
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method's return.</p>
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<hr size=1 noshade>
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<br><b>Class</b>
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<a href="../api_c/env_class.html">DB_ENV</a>, DB_MPOOLFILE
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<br><b>See Also</b>
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<a href="../api_c/memp_list.html">Memory Pools and Related Methods</a>
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</tt>
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<table width="100%"><tr><td><br></td><td align=right>
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<a href="../api_c/api_core.html"><img src="../images/api.gif" alt="API"></a><a href="../ref/toc.html"><img src="../images/ref.gif" alt="Ref"></a>
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</td></tr></table>
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<p><font size=1>Copyright (c) 1996,2008 Oracle. All rights reserved.</font>
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</body>
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</html>
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