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https://github.com/yasuhirokimura/db18
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Yasuhiro KIMURA
209 lines
7.5 KiB
HTML
209 lines
7.5 KiB
HTML
<?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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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
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<title>DB_ENV->set_ext_file_threshold()</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="blob.html" title="Chapter 13. External Files" />
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<link rel="prev" href="envset_blob_dir.html" title="DB_ENV->set_ext_file_dir()" />
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<link rel="next" href="utilities.html" title="Appendix A. Berkeley DB Command Line Utilities" />
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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 18.1.40</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">
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<span xmlns="http://www.w3.org/1999/xhtml">DB_ENV->set_ext_file_threshold()</span>
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</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="envset_blob_dir.html">Prev</a> </td>
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<th width="60%" align="center">Chapter 13.
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External Files
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</th>
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<td width="20%" align="right"> <a accesskey="n" href="utilities.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="envset_blob_threshold"></a>
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<span>DB_ENV->set_ext_file_threshold()</span>
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</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_ENV->set_ext_file_threshold(DB_ENV *dbenv, u_int32_t bytes,
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u_int32_t flags); </pre>
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<p>
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The <code class="methodname">DB_ENV->set_ext_file_threshold()</code> method sets
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a default size for the environment which is used to determine when
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a data item will be stored as an external file. Data items sized less
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than this threshold are stored as normal data within the database. Data
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items larger than this size are stored on-disk in a subdirectory
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set aside for the purpose.
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</p>
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<p>
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If this threshold value is set to <code class="literal">0</code>, then external
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file support is turned off by default for databases created in the
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environment. If this method is never called, then the default external
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file threshold is <code class="literal">0</code>.
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</p>
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<p>
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This method only sets the default external file threshold for the
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environment. The external file threshold can be set for individual
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databases created within the environment using
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<a class="xref" href="set_blob_threshold.html" title="DB->set_ext_file_threshold()">
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<span>DB->set_ext_file_threshold()</span>
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</a>.
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</p>
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<p>
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This method configures operations performed using the specified
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<a class="link" href="env.html" title="Chapter 5. The DB_ENV Handle">DB_ENV</a> handle, not all operations
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performed on the underlying database environment.
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</p>
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<p>
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You may call this method at any time after the DB_ENV handle
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has been created.
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</p>
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<p>
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Unless otherwise specified, the
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<code class="methodname">DB_ENV->set_ext_file_threshold()</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="idm139753795348240"></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="idm139753795348624"></a>bytes</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>bytes</strong></span> parameter
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identifies the threshold size, in bytes, beyond which a
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data item is stored as an external file.
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</p>
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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="idm139753795366320"></a>flags</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>flags</strong></span> parameter must be
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set to 0.
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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="idm139753795471280"></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_ENV->set_ext_file_threshold()</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="idm139753795367840"></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 an invalid flag 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="idm139753795335840"></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="env.html" title="Chapter 5. The DB_ENV Handle">DB_ENV</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="idm139753795360176"></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="blob.html#bloblist" title="External Files and Related Methods">External Files 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="envset_blob_dir.html">Prev</a> </td>
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<td width="20%" align="center">
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<a accesskey="u" href="blob.html">Up</a>
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</td>
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<td width="40%" align="right"> <a accesskey="n" href="utilities.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">
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<span>DB_ENV->set_ext_file_dir()</span>
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</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"> Appendix A.
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Berkeley DB Command Line Utilities
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</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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