82 lines
3.6 KiB
HTML
82 lines
3.6 KiB
HTML
<!--$Id: memp_set_clear_len.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: DbMpoolFile::set_clear_len</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>DbMpoolFile::set_clear_len</b>
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</td>
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<td align=right>
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<a href="../api_cxx/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_cxx.h>
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<p>
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int
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DbMpoolFile::set(u_int32_t len);
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<p>
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int
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DbMpoolFile::get_clear_len(u_int32_t *lenp);
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</pre></b>
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<hr size=1 noshade>
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<b>Description: DbMpoolFile::set_clear_len</b>
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<p>The DbMpoolFile::set_clear_len method sets the number of initial bytes in a
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page that should be set to nul when the page is created as a result of
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the <a href="../api_cxx/memp_fget.html#DB_MPOOL_CREATE">DB_MPOOL_CREATE</a> or <a href="../api_cxx/memp_fget.html#DB_MPOOL_NEW">DB_MPOOL_NEW</a> flags being
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specified to <a href="../api_cxx/memp_fget.html">DbMpoolFile::get</a>. If no clear length is specified, the
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entire page is cleared when it is created.</p>
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<p>The DbMpoolFile::set_clear_len method configures a file in the memory pool, not only
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operations performed using the specified <a href="../api_cxx/mempfile_class.html">DbMpoolFile</a> handle.</p>
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<p>The DbMpoolFile::set_clear_len method may not be called after the <a href="../api_cxx/memp_fopen.html">DbMpoolFile::open</a> method is
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called.
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If the file is already open in the memory pool when
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<a href="../api_cxx/memp_fopen.html">DbMpoolFile::open</a> is called, the information specified to DbMpoolFile::set_clear_len
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must be consistent with the existing file or an error will be
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returned.
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</p>
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<p>The DbMpoolFile::set_clear_len method
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either returns a non-zero error value
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or throws an exception that encapsulates a non-zero error value on
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failure, and returns 0 on success.
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</p>
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<b>Parameters</b> <br>
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<b>len</b><ul compact><li>The <b>len</b> parameter is the number of initial bytes in a page that
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should be set to nul when the page is created. A value of 0 results in
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the entire page being set to nul bytes.</ul>
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<br>
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<hr size=1 noshade>
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<b>Description: DbMpoolFile::get_clear_len</b>
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<p>The DbMpoolFile::get_clear_len method returns the bytes to be cleared.</p>
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<p>The DbMpoolFile::get_clear_len method may be called at any time during the life of the
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application.</p>
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<p>The DbMpoolFile::get_clear_len method
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either returns a non-zero error value
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or throws an exception that encapsulates a non-zero error value on
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failure, and returns 0 on success.
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</p>
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<b>Parameters</b> <br>
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<b>lenp</b><ul compact><li>The DbMpoolFile::get_clear_len method returns the
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bytes to be cleared in <b>lenp</b>.</ul>
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<br>
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<hr size=1 noshade>
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<br><b>Class</b>
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<a href="../api_cxx/env_class.html">DbEnv</a>, <a href="../api_cxx/mempfile_class.html">DbMpoolFile</a>
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<br><b>See Also</b>
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<a href="../api_cxx/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_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>
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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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