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141 lines
5.7 KiB
HTML
141 lines
5.7 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>Bulk Transfers</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="c2ctransfer.html" title="Client to Client Transfer" />
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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 11.2.5.3</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">Bulk Transfers</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="c2ctransfer.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"> </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="bulk"></a>Bulk Transfers</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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By default, messages are sent from the master to replicas as they are generated.
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This can degrade replication performance because the various participating
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environments must handle a fair amount of network I/O activity.
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</p>
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<p>
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You can alleviate this problem by configuring your master environment for bulk
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transfers. Bulk transfers simply cause replication messages to accumulate in a
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buffer until a triggering event occurs. When this event occurs, the entire
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contents of the buffer is sent to the replica, thereby eliminating excessive
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network I/O.
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</p>
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<p>
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Note that if you are using replica to replica transfers, then you might want any
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replica that can service replication requests to also be configured for bulk
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transfers.
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</p>
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<p>
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The events that result in a bulk transfer of replication messages to a replica
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will differ depending on if the transmitting environment is a master or a
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replica.
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</p>
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<p>
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If the servicing environment is a master environment, then bulk transfer
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occurs when:
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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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Bulk transfers are configured for the master environment, and
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</p>
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</li>
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<li>
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<p>
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the message buffer is full or
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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 permanent record (for example, a transaction commit or a
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checkpoint record) is placed in the buffer for the replica.
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</p>
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</li>
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</ol>
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</div>
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<p>
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If the servicing environment is a replica environment (that is, replica to replica
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transfers are in use), then a bulk transfer occurs when:
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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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Bulk transfers are configured for the transmitting replica, and
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</p>
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</li>
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<li>
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<p>
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the message buffer is full or
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</p>
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</li>
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<li>
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<p>
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the replica servicing the request is able to completely satisfy
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the request with the contents of the message buffer.
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</p>
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</li>
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</ol>
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</div>
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<p>
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To configure bulk transfers, specify
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<span>
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<code class="literal">DB_REP_CONF_BULK</code> to
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<code class="methodname">DB_ENV->rep_set_config()</code>
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and then specify <code class="literal">1</code> to the <code class="literal">onoff</code>
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parameter. (Specify <code class="literal">0</code> to turn the feature off.)
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</span>
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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="c2ctransfer.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"> </td>
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</tr>
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<tr>
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<td width="40%" align="left" valign="top">Client to Client Transfer </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"> </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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