Edit File: bulk.html
<?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> <title>Bulk Transfers</title> <link rel="stylesheet" href="gettingStarted.css" type="text/css" /> <meta name="generator" content="DocBook XSL Stylesheets V1.62.4" /> <link rel="home" href="index.html" title="Getting Started with Replicated Berkeley DB Applications" /> <link rel="up" href="addfeatures.html" title="Chapter 5. Additional Features" /> <link rel="previous" href="c2ctransfer.html" title="Client to Client Transfer" /> </head> <body> <div class="navheader"> <table width="100%" summary="Navigation header"> <tr> <th colspan="3" align="center">Bulk Transfers</th> </tr> <tr> <td width="20%" align="left"><a accesskey="p" href="c2ctransfer.html">Prev</a> </td> <th width="60%" align="center">Chapter 5. Additional Features</th> <td width="20%" align="right"> </td> </tr> </table> <hr /> </div> <div class="sect1" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h2 class="title" style="clear: both"><a id="bulk"></a>Bulk Transfers</h2> </div> </div> <div></div> </div> <p> By default, messages are sent from the master to replicas as they are generated. This can degrade replication performance because the various participating environments must handle a fair amount of network I/O activity. </p> <p> You can alleviate this problem by configuring your master environment for bulk transfers. Bulk transfers simply cause replication messages to accumulate in a buffer until a triggering event occurs. When this event occurs, the entire contents of the buffer is sent to the replica, thereby eliminating excessive network I/O. </p> <p> Note that if you are using replica to replica transfers, then you might want any replica that can service replication requests to also be configured for bulk transfers. </p> <p> The events that result in a bulk transfer of replication messages to a replica will differ depending on if the transmitting environment is a master or a replica. </p> <p> If the servicing environment is a master environment, then bulk a bulk transfer occurs when: </p> <div class="orderedlist"> <ol type="1"> <li> <p> Bulk transfers are configured for the master environment, and </p> </li> <li> <p> the message buffer is full or </p> </li> <li> <p> a permanent record (for example, a transaction commit or a checkpoint record) is placed in the buffer for the replica. </p> </li> </ol> </div> <p> If the servicing environment is a replica environment (that is, replica to replica transfers are in use), then a bulk transfer occurs when: </p> <div class="orderedlist"> <ol type="1"> <li> <p> Bulk transfers are configured for the transmitting replica, and </p> </li> <li> <p> the message buffer is full or </p> </li> <li> <p> the replica servicing the request is able to completely satisfy the request with the contents of the message buffer. </p> </li> </ol> </div> <p> To configure bulk transfers, specify <span> <tt class="literal">DB_REP_CONF_BULK</tt> to <tt class="methodname">DB_ENV->rep_set_config()</tt> and then specify <tt class="literal">1</tt> to the <tt class="literal">onoff</tt> parameter. (Specify <tt class="literal">0</tt> to turn the feature off.) </span> </p> </div> <div class="navfooter"> <hr /> <table width="100%" summary="Navigation footer"> <tr> <td width="40%" align="left"><a accesskey="p" href="c2ctransfer.html">Prev</a> </td> <td width="20%" align="center"> <a accesskey="u" href="addfeatures.html">Up</a> </td> <td width="40%" align="right"> </td> </tr> <tr> <td width="40%" align="left" valign="top">Client to Client Transfer </td> <td width="20%" align="center"> <a accesskey="h" href="index.html">Home</a> </td> <td width="40%" align="right" valign="top"> </td> </tr> </table> </div> </body> </html>
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