2011-09-13 17:44:24 +00:00
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<title>Chapter 5. Additional Features</title>
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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="index.html" title="Getting Started with Replicated Berkeley DB Applications" />
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<link rel="prev" href="exampledoloop.html" title="Example Processing Loop" />
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<link rel="next" href="manageblock.html" title="Managing Blocking Operations" />
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<body>
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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">Chapter 5. Additional Features</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="exampledoloop.html">Prev</a> </td>
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<th width="60%" align="center"> </th>
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<td width="20%" align="right"> <a accesskey="n" href="manageblock.html">Next</a></td>
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</table>
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<hr />
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</div>
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<div class="chapter" 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"><a id="addfeatures"></a>Chapter 5. Additional Features</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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<p>
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<b>Table of Contents</b>
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</p>
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<dl>
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<dt>
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<span class="sect1">
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<a href="addfeatures.html#delayedsync">Delayed Synchronization</a>
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</span>
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</dt>
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<dt>
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<span class="sect1">
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<a href="manageblock.html">Managing Blocking Operations</a>
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</span>
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</dt>
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<dt>
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<span class="sect1">
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<a href="autoinit.html">Stop Auto-Initialization</a>
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</span>
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</dt>
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<dt>
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<span class="sect1">
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<a href="rywc.html">Read-Your-Writes Consistency</a>
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</span>
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</dt>
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<dt>
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<span class="sect1">
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<a href="c2ctransfer.html">Client to Client Transfer</a>
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</span>
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</dt>
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<dd>
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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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</dd>
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<dt>
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<span class="sect1">
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<a href="bulk.html">Bulk Transfers</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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Beyond the basic functionality that we have discussed so far in
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this book, there are several replication features that you
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should understand. These are all optional to use, but provide
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useful functionality under the right circumstances.
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</p>
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<p>
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These additional features are:
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</p>
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<div class="orderedlist">
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<ol type="1">
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<li>
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<p>
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<a class="xref" href="addfeatures.html#delayedsync" title="Delayed Synchronization">Delayed Synchronization</a>
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</p>
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</li>
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<li>
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<p>
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<a class="xref" href="manageblock.html" title="Managing Blocking Operations">Managing Blocking Operations</a>
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</p>
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</li>
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<li>
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<p>
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<a class="xref" href="autoinit.html" title="Stop Auto-Initialization">Stop Auto-Initialization</a>
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</p>
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</li>
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<li>
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<p>
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<a class="xref" href="c2ctransfer.html" title="Client to Client Transfer">Client to Client Transfer</a>
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</p>
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</li>
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<li>
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<p>
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<a class="xref" href="bulk.html" title="Bulk Transfers">Bulk Transfers</a>
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</p>
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</li>
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</ol>
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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="delayedsync"></a>Delayed Synchronization</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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When a replication group has a new master, all replicas must
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synchronize with that master. This means they must ensure
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that the contents of their local database(s) are identical
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to that contained by the new master.
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</p>
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<p>
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This synchronization process can result in quite a lot of
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network activity. It can also put a large strain on the
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master server, especially if is part of a large
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replication group or if there is somehow a large difference between
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the master's database(s) and the contents of its replicas.
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</p>
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<p>
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It is therefore possible to delay synchronization for any
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replica that discovers it has a new master. You would do
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this so as to give the master time to synchronize other
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replicas before proceeding with the delayed replicas.
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</p>
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<p>
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To delay synchronization of a replica environment, you
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specify
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<span>
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<code class="literal">ReplicationConfig.DELAYCLIENT</code> and
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<code class="literal">true</code> to
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<code class="methodname">Environment.setReplicationConfig()</code>.
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To turn off delayed synchronization, specify
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<code class="literal">false</code> for the
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<code class="literal">ReplicationConfig.DELAYCLIENT</code> field.
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</span>
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</p>
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<p>
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If you use delayed synchronization, then you must manually
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synchronize the replica at some future time. Until you do this, the replica is out of
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sync with the master, and it will ignore all database changes forwarded to it from
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the master.
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</p>
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<p>
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You synchronize a delayed replica by calling
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<code class="methodname">Environment.syncReplication()</code>
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on the replica that has been delayed.
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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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<td width="40%" align="left"><a accesskey="p" href="exampledoloop.html">Prev</a> </td>
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<td width="20%" align="center"> </td>
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<td width="40%" align="right"> <a accesskey="n" href="manageblock.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">Example Processing Loop </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"> Managing Blocking Operations</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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