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https://github.com/yasuhirokimura/db18
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Yasuhiro KIMURA
225 lines
12 KiB
HTML
225 lines
12 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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<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>Replication Manager methods</title>
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<link rel="stylesheet" href="gettingStarted.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 Programmer's Reference Guide" />
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<link rel="up" href="rep.html" title="Chapter 12. Berkeley DB Replication" />
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<link rel="prev" href="rep_app.html" title="Building replicated applications" />
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<link rel="next" href="rep_base_meth.html" title="Base API methods" />
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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">Replication Manager methods</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="rep_app.html">Prev</a> </td>
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<th width="60%" align="center">Chapter 12. Berkeley DB Replication </th>
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<td width="20%" align="right"> <a accesskey="n" href="rep_base_meth.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="rep_mgr_meth"></a>Replication Manager methods</h2>
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</div>
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</div>
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</div>
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<p>
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Applications which use the Replication Manager support
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generally call the following Berkeley DB methods. The general
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pattern is to call various methods to configure Replication
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Manager, and then start it by calling <a href="../api_reference/C/repmgrstart.html" class="olink">DB_ENV->repmgr_start()</a>. Once this
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initialization is complete, the application rarely needs to
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call any of these methods. (A prime example of an exception to
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this rule would be the <a href="../api_reference/C/repsync.html" class="olink">DB_ENV->rep_sync()</a> method, if the application is
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<a class="xref" href="rep_mastersync.html#rep_delay_sync" title="Delaying client synchronization">Delaying client synchronization</a>.)
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</p>
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<div class="variablelist">
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<dl>
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<dt>
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<span class="term">
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<a href="../api_reference/C/db_site.html" class="olink">DB_SITE</a>
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</span>
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</dt>
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<dd>
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<p>
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The <a href="../api_reference/C/db_site.html" class="olink">DB_SITE</a> handle is used to configure a site
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that belongs to the replication group. You can
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obtain a <a href="../api_reference/C/db_site.html" class="olink">DB_SITE</a> handle by calling the
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<a href="../api_reference/C/repmgr_site.html" class="olink">DB_ENV->repmgr_site()</a> method. When you do this, you
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provide the TCP/IP host name and port that the
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replication site uses for incoming connections.
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</p>
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<p>
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Once you have the <a href="../api_reference/C/db_site.html" class="olink">DB_SITE</a> handle, you use the
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<a href="../api_reference/C/dbsite_set_config.html" class="olink">DB_SITE->set_config()</a> method to configure the
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handle. One of the things you can configure about
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the handle is whether it is the local site (using
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the <code class="literal">DB_LOCAL_SITE</code> parameter).
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You must configure one and only one <a href="../api_reference/C/db_site.html" class="olink">DB_SITE</a>
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handle to be a local site before you start
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replication.
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</p>
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<p>
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You can also optionally configure <a href="../api_reference/C/db_site.html" class="olink">DB_SITE</a>
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handles for remote sites to help Replication
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Manager start up more efficiently. Note that it is
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usually not necessary for each site in the
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replication group initially to know about all
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other sites in the group. Sites can discover each
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other dynamically, as described in <a class="xref" href="rep_newsite.html" title="Connecting to a new site">Connecting to a new site</a>.
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</p>
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<p>
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Once you have configured your <a href="../api_reference/C/db_site.html" class="olink">DB_SITE</a> handles,
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you start replication using <a href="../api_reference/C/repmgrstart.html" class="olink">DB_ENV->repmgr_start()</a>.
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</p>
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<p>
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When you are shutting down your application,
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you must use the <a href="../api_reference/C/dbsite_close.html" class="olink">DB_SITE->close()</a> method to close
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all your open <a href="../api_reference/C/db_site.html" class="olink">DB_SITE</a> handles before you close
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your environment handles.
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</p>
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</dd>
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<dt>
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<span class="term">
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<a href="../api_reference/C/repmgrset_ack_policy.html" class="olink">DB_ENV->repmgr_set_ack_policy()</a>
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</span>
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</dt>
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<dd>
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<p>
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The <a href="../api_reference/C/repmgrset_ack_policy.html" class="olink">DB_ENV->repmgr_set_ack_policy()</a> method configures the
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acknowledgement policy to be used in the
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replication group, in other words, the behavior of
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the master with respect to acknowledgements for
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"permanent" messages, which implements the
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application's requirements for <a class="xref" href="rep_trans.html" title="Transactional guarantees">Transactional guarantees</a>.
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The current implementation requires all sites
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in the replication group to configure the same
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acknowledgement policy.
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</p>
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</dd>
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<dt>
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<span class="term">
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<a href="../api_reference/C/reppriority.html" class="olink">DB_ENV->rep_set_priority()</a>
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</span>
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</dt>
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<dd>
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<p>
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The <a href="../api_reference/C/reppriority.html" class="olink">DB_ENV->rep_set_priority()</a> method configures the local
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site's priority for the purpose of elections.
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</p>
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</dd>
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<dt>
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<span class="term">
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<a href="../api_reference/C/repset_timeout.html" class="olink">DB_ENV->rep_set_timeout()</a>
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</span>
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</dt>
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<dd>
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<p>
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This method optionally configures various
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timeout values. Otherwise default timeout values
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as specified in <a href="../api_reference/C/repset_timeout.html" class="olink">DB_ENV->rep_set_timeout()</a> are used. In
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particular, Replication Manager client sites can
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be configured to monitor the health of the TCP/IP
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connection to the master site using heartbeat
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messages. If the client receives no messages from
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the master for a certain amount of time, it
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considers the connection to be broken, and calls
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for an election to choose a new master. Heartbeat
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messages also help clients request missing master
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changes in the absence of master activity.
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</p>
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</dd>
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<dt>
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<span class="term">
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<a href="../api_reference/C/envevent_notify.html" class="olink">DB_ENV->set_event_notify()</a>
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</span>
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</dt>
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<dd>
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<p>
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Once configured and started, Replication
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Manager does virtually all of its work in the
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background, usually without the need for any
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direct communication with the application.
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However, occasionally events occur which the
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application may be interested in knowing about.
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The application can request notification of these
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events by calling the <a href="../api_reference/C/envevent_notify.html" class="olink">DB_ENV->set_event_notify()</a> method.
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</p>
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</dd>
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<dt>
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<span class="term">
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<a href="../api_reference/C/repmgrstart.html" class="olink">DB_ENV->repmgr_start()</a>
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</span>
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</dt>
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<dd>
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<p>
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The <a href="../api_reference/C/repmgrstart.html" class="olink">DB_ENV->repmgr_start()</a> method starts the replication
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system. It opens the listening TCP/IP socket and
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creates all the background processing threads that
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will be needed.
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</p>
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</dd>
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</dl>
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</div>
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<p>
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In addition to the methods previously described,
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Replication Manager applications may also call the following
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methods, as needed: <a href="../api_reference/C/repconfig.html" class="olink">DB_ENV->rep_set_config()</a>, <a href="../api_reference/C/repset_limit.html" class="olink">DB_ENV->rep_set_limit()</a>, <a href="../api_reference/C/repset_request.html" class="olink">DB_ENV->rep_set_request()</a>,
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<a href="../api_reference/C/repsync.html" class="olink">DB_ENV->rep_sync()</a> and <a href="../api_reference/C/repstat.html" class="olink">DB_ENV->rep_stat()</a>.
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</p>
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<p>
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If a Replication Manager replication group contains only two
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sites and one particular site should be master whenever
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possible, the replication group can be configured to run in
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preferred master mode. For more information, see
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<a class="xref" href="rep_twosite.html#twosite_prefmas" title="Preferred master mode">Preferred master mode</a>.
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</p>
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<p>
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Replication Manager applications may configure one or more
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view sites. A view is a full or partial copy of the replicated
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data that does not otherwise participate in the replication
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group. For more information, see <a class="xref" href="rep_partview.html" title="Replication views">Replication views</a>.
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</p>
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<p>
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Finally, Replication Manager applications can also make use
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of the Replication Manager's message channels. This allows the
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various sites in the replication group to pass messages that
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are tailored to the application's requirements. For more
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information, see <a class="xref" href="comm_repsites.html#repmgr_channels" title="Using Replication Manager message channels">Using Replication Manager message channels</a>.
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</p>
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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="rep_app.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="rep_base_meth.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">Building replicated applications </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"> Base API methods</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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