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Yasuhiro KIMURA
229 lines
8.9 KiB
HTML
229 lines
8.9 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->rep_set_priority()</title>
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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="rep.html" title="Chapter 10. Replication Methods" />
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<link rel="prev" href="repnsites.html" title="DB_ENV->rep_set_nsites()" />
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<body>
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<div xmlns="" class="navheader">
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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->rep_set_priority()</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="repnsites.html">Prev</a> </td>
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<th width="60%" align="center">Chapter 10.
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Replication Methods
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</th>
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<td width="20%" align="right"> <a accesskey="n" href="repset_request.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="reppriority"></a>
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<span>DB_ENV->rep_set_priority()</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->rep_set_priority(DB_ENV *env, u_int32_t priority); </pre>
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<p>
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The <code class="methodname">DB_ENV->rep_set_priority()</code> method specifies the database
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environment's priority in replication group elections. A special
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value of 0 indicates that this environment cannot be a replication
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group master.
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</p>
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<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
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<h3 class="title">Note</h3>
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<p>
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The
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<a class="xref" href="repmgrset_ack_policy.html" title="DB_ENV->repmgr_set_ack_policy()">
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<span>DB_ENV->repmgr_set_ack_policy()</span>
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</a>
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method describes <span class="emphasis"><em>electable peers</em></span>, which
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are replication sites with a non-zero priority. For some
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acknowledgement policies, Replication Manager's computation of
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the durability result for each new update transaction is
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sensitive to whether each site in the group is a peer.
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Therefore, if you change a site's priority from a non-zero
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value to <code class="literal">0</code>, or from <code class="literal">0</code> to
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a non-zero value, this can invalidate the durability result of
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previously committed transactions.
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</p>
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</div>
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<p>
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The database environment's replication subsystem may also be
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configured using the environment's <a href="../../programmer_reference/env_db_config.html#env_db_config.DB_CONFIG" class="olink">DB_CONFIG</a> file. The syntax
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of the entry in that file is a single line with the string
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"rep_set_priority", one or more whitespace characters, and the
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priority of this site. For example, "rep_set_priority 1" sets the
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priority of this site to 1. Because the <a href="../../programmer_reference/env_db_config.html#env_db_config.DB_CONFIG" class="olink">DB_CONFIG</a> file is read
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when the database environment is opened, it will silently overrule
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configuration done before that time.
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</p>
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<p>
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Note that if the application never explicitly sets a priority, then
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a default value of 100 is used. In preferred master mode, priority
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values for each site are automatically set and any attempt to change
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them results in an error.
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</p>
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<p>
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The <code class="methodname">DB_ENV->rep_set_priority()</code> method configures a database
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environment, not only 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.
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</p>
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<p>
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The <code class="methodname">DB_ENV->rep_set_priority()</code> method may be called at any time
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during the life of the application.
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</p>
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<p>
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The <code class="methodname">DB_ENV->rep_set_priority()</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="idm139753797381392"></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="idm139753797380240"></a>priority</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 priority of this database environment in the replication group. The
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priority must be a non-zero integer, or 0 if this environment cannot be a
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replication group master. (See
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<a href="../../programmer_reference/rep_pri.html" class="olink">Replication environment priorities</a>
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for more information).
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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="idm139753797388528"></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->rep_set_priority()</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="idm139753797364032"></a>DB_REP_INELECT</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 attempting to change the database environment's
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priority while an election is in progress.
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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="idm139753797351408"></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 changing the automatically set priority value in
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Replication Manager preferred master mode.
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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="idm139753797373248"></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="idm139753797381072"></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="rep.html#replist" title="Replication and Related Methods">Replication 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="repnsites.html">Prev</a> </td>
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<td width="20%" align="center">
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<a accesskey="u" href="rep.html">Up</a>
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</td>
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<td width="40%" align="right"> <a accesskey="n" href="repset_request.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->rep_set_nsites()</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">
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<span>DB_ENV->rep_set_request()</span>
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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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