2011-09-13 17:44:24 +00:00
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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>Client to Client Transfer</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="Getting Started with Replicated Berkeley DB Applications" />
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<link rel="up" href="addfeatures.html" title="Chapter 5. Additional Features" />
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<link rel="prev" href="rywc.html" title="Read-Your-Writes Consistency" />
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<link rel="next" href="bulk.html" title="Bulk Transfers" />
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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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2012-11-14 21:35:20 +00:00
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<p>Library Version 11.2.5.3</p>
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2011-09-13 17:44:24 +00:00
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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">Client to Client Transfer</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="rywc.html">Prev</a> </td>
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<th width="60%" align="center">Chapter 5. Additional Features</th>
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<td width="20%" align="right"> <a accesskey="n" href="bulk.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="c2ctransfer"></a>Client to Client Transfer</h2>
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</div>
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</div>
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</div>
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<div class="toc">
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<dl>
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<dt>
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<span class="sect2">
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<a href="c2ctransfer.html#fmwrkpeerserver">Identifying Peers</a>
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</span>
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</dt>
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</dl>
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</div>
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<p>
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It is possible to use a replica instead of a master to synchronize another
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replica. This serves to take the request load off a master that might otherwise
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occur if multiple replicas attempted to synchronize with the master at the same
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time.
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</p>
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<p>
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For best results, use this feature combined with the delayed synchronization
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feature (see <a class="xref" href="addfeatures.html#delayedsync" title="Delayed Synchronization">Delayed Synchronization</a>).
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</p>
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<p>
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For example, suppose your replication group consists of four environments. Upon
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application startup, all three replicas will immediately attempt to synchronize
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with the master. But at the same time, the master itself might be busy with a heavy
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database write load.
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</p>
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<p>
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To solve this problem, delay synchronization for two of the three replicas. Allow
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the third replica to synchronize as normal with the master. Then, start
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synchronization for each of the delayed replicas (since this is a manual process,
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you can do them one at a time if that best suits your application).
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Assuming you have configured replica to replica synchronization correctly, the
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delayed replicas will synchronize using the up-to-date replica, rather than using
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the master.
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</p>
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<p>
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When you are using the Replication Manager, you configure replica to replica synchronization by
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declaring an environment to be a peer of another environment. If an
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environment is a peer, then it can be used for synchronization purposes.
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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="fmwrkpeerserver"></a>Identifying Peers</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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You can designate one replica to be a peer of
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another for replica to replica synchronization.
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You might want to do this if you have
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machines that you know are on fast, reliable
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network connections and so you are willing to
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accept the overhead of waiting for
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acknowledgments from those specific machines.
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</p>
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<p>
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Note that peers are not required to be a
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bi-directional. That is, just because machine A
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declares machine B to be a peer, that does not mean
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machine B must also declare machine A to be a peer.
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</p>
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<p>
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You declare a peer for the current environment
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when you add that environment to the list of known
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sites. You do this by
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<span>specifying the
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<code class="literal">DB_REPMGR_PEER</code> flag to
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<span><code class="methodname">DbEnv::repmgr_add_remote_site()</code>.</span>
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</span>
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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="rywc.html">Prev</a> </td>
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<td width="20%" align="center">
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<a accesskey="u" href="addfeatures.html">Up</a>
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</td>
|
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<td width="40%" align="right"> <a accesskey="n" href="bulk.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">Read-Your-Writes Consistency </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"> Bulk Transfers</td>
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</tr>
|
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</table>
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|
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</div>
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</body>
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</html>
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