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<h1>DbMpoolFile::set_clear_len</h1>
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<h3><pre>
#include <db_cxx.h>
<p>
int
DbMpoolFile::set(u_int32_t len);
</pre></h3>
<h1>Description</h1>
<p>The DbMpoolFile::set_clear_len method sets the number of initial bytes in a
page that should be set to nul when the page is created as a result of
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
specified to <a href="../api_cxx/memp_fget.html">DbMpoolFile::get</a>. If no value is specified, or <b>len</b>
is 0, the entire page is cleared.
<p>The DbMpoolFile::set_clear_len method configures a file in the memory pool, not only
operations performed using the specified <a href="../api_cxx/mempfile_class.html">DbMpoolFile</a> handle.
<p>The DbMpoolFile::set_clear_len interface may not be called after the <a href="../api_cxx/memp_fopen.html">DbMpoolFile::open</a>
interface is called.
If the file is already open in the memory pool when
<a href="../api_cxx/memp_fopen.html">DbMpoolFile::open</a> is called, the information specified to DbMpoolFile::set_clear_len
must be consistent with the existing file or an error will be
returned.
<p>The DbMpoolFile::set_clear_len 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.
<h1>Errors</h1>
<p>The DbMpoolFile::set_clear_len method may fail and throw an exception or return a non-zero error for errors specified for other Berkeley DB and C library or system methods.
If a catastrophic error has occurred, the DbMpoolFile::set_clear_len method may fail and
either return <a href="../ref/program/errorret.html#DB_RUNRECOVERY">DB_RUNRECOVERY</a> or throw a
<a href="../api_cxx/runrec_class.html">DbRunRecoveryException</a>,
in which case all subsequent Berkeley DB calls will fail in the same way.
<h1>Class</h1>
<a href="../api_cxx/env_class.html">DbEnv</a>, <a href="../api_cxx/mempfile_class.html">DbMpoolFile</a>
<h1>See Also</h1>
<a href="../api_cxx/memp_list.html">Memory Pools and Related Methods</a>
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