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173 lines
6.5 KiB
HTML
173 lines
6.5 KiB
HTML
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<?xml version="1.0" encoding="UTF-8" standalone="no"?>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml">
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
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<title>DB->set_h_nelem()</title>
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<link rel="stylesheet" href="apiReference.css" type="text/css" />
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<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
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<link rel="start" href="index.html" title="Berkeley DB C API Reference" />
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<link rel="up" href="db.html" title="Chapter 2. The DB Handle" />
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<link rel="prev" href="dbset_h_hash.html" title="DB->set_h_hash()" />
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<link rel="next" href="dbset_heapsize.html" title="DB->set_heapsize()" />
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</head>
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<body>
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<div xmlns="" class="navheader">
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<div class="libver">
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<p>Library Version 11.2.5.2</p>
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</div>
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<table width="100%" summary="Navigation header">
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<tr>
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<th colspan="3" align="center">DB->set_h_nelem()</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="dbset_h_hash.html">Prev</a> </td>
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<th width="60%" align="center">Chapter 2.
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The DB Handle
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</th>
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<td width="20%" align="right"> <a accesskey="n" href="dbset_heapsize.html">Next</a></td>
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</tr>
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</table>
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<hr />
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</div>
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<div class="sect1" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h2 class="title" style="clear: both"><a id="dbset_h_nelem"></a>DB->set_h_nelem()</h2>
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</div>
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</div>
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</div>
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<pre class="programlisting">#include <db.h>
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int
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DB->set_h_nelem(DB *db, u_int32_t h_nelem); </pre>
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<p>
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Set an estimate of the final size of the hash table.
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</p>
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<p>
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In order for the estimate to be used when creating the database, the
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<a class="xref" href="dbset_h_ffactor.html" title="DB->set_h_ffactor()">DB->set_h_ffactor()</a>
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method must also be called. If the estimate or fill factor are not
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set or are set too low, hash tables will still expand gracefully as
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keys are entered, although a slight performance degradation may be
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noticed.
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</p>
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<p>
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The <code class="methodname">DB->set_h_nelem()</code> method configures a database, not only
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operations performed using the specified <a class="link" href="db.html" title="Chapter 2. The DB Handle">DB</a>
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handle.
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</p>
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<p>
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The <code class="methodname">DB->set_h_nelem()</code> method may not be called after the
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<a class="xref" href="dbopen.html" title="DB->open()">DB->open()</a> method is called. If
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the database already exists when <a class="xref" href="dbopen.html" title="DB->open()">DB->open()</a>
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is called, the information specified to <code class="methodname">DB->set_h_nelem()</code> will be ignored.
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</p>
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<p>
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The <code class="methodname">DB->set_h_nelem()</code> <span>
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<span>
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method returns a non-zero error value on failure and 0 on success.
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</span>
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</span>
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</p>
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<div class="sect2" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h3 class="title"><a id="id3870117"></a>Parameters</h3>
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</div>
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</div>
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</div>
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<div class="sect3" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h4 class="title"><a id="id3870278"></a>h_nelem</h4>
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</div>
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</div>
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</div>
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<p>
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The <span class="bold"><strong>h_nelem</strong></span> parameter is an estimate
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of the final size of the hash table.
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</p>
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</div>
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</div>
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<div class="sect2" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h3 class="title"><a id="id3869823"></a>Errors</h3>
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</div>
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</div>
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</div>
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<p>
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The <code class="methodname">DB->set_h_nelem()</code> <span>
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<span>
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method may fail and return one of the following non-zero errors:
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</span>
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</span>
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</p>
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<div class="sect3" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h4 class="title"><a id="id3870381"></a>EINVAL</h4>
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</div>
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</div>
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</div>
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<p>
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If the method was called after <a class="xref" href="dbopen.html" title="DB->open()">DB->open()</a>
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was called; or if an invalid flag value or parameter was specified.
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</p>
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</div>
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</div>
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<div class="sect2" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h3 class="title"><a id="id3870363"></a>Class</h3>
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</div>
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</div>
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</div>
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<p>
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<a class="link" href="db.html" title="Chapter 2. The DB Handle">DB</a>
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</p>
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</div>
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<div class="sect2" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h3 class="title"><a id="id3870416"></a>See Also</h3>
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</div>
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</div>
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</div>
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<p>
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<a class="xref" href="db.html#dblist" title="Database and Related Methods">Database and Related Methods</a>
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</p>
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</div>
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</div>
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<div class="navfooter">
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<hr />
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<table width="100%" summary="Navigation footer">
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<tr>
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<td width="40%" align="left"><a accesskey="p" href="dbset_h_hash.html">Prev</a> </td>
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<td width="20%" align="center">
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<a accesskey="u" href="db.html">Up</a>
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</td>
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<td width="40%" align="right"> <a accesskey="n" href="dbset_heapsize.html">Next</a></td>
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</tr>
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<tr>
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<td width="40%" align="left" valign="top">DB->set_h_hash() </td>
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<td width="20%" align="center">
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<a accesskey="h" href="index.html">Home</a>
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</td>
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<td width="40%" align="right" valign="top"> DB->set_heapsize()</td>
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</tr>
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</table>
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</div>
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</body>
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</html>
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