1<?xml version="1.0" encoding="UTF-8" standalone="no"?> 2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 3<html xmlns="http://www.w3.org/1999/xhtml"> 4 <head> 5 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> 6 <title>Bulk Transfers</title> 7 <link rel="stylesheet" href="gettingStarted.css" type="text/css" /> 8 <meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /> 9 <link rel="start" href="index.html" title="Getting Started with Replicated Berkeley DB Applications" /> 10 <link rel="up" href="addfeatures.html" title="Chapter 5. Additional Features" /> 11 <link rel="prev" href="c2ctransfer.html" title="Client to Client Transfer" /> 12 </head> 13 <body> 14 <div class="navheader"> 15 <table width="100%" summary="Navigation header"> 16 <tr> 17 <th colspan="3" align="center">Bulk Transfers</th> 18 </tr> 19 <tr> 20 <td width="20%" align="left"><a accesskey="p" href="c2ctransfer.html">Prev</a> </td> 21 <th width="60%" align="center">Chapter 5. Additional Features</th> 22 <td width="20%" align="right"> </td> 23 </tr> 24 </table> 25 <hr /> 26 </div> 27 <div class="sect1" lang="en" xml:lang="en"> 28 <div class="titlepage"> 29 <div> 30 <div> 31 <h2 class="title" style="clear: both"><a id="bulk"></a>Bulk Transfers</h2> 32 </div> 33 </div> 34 </div> 35 <p> 36 By default, messages are sent from the master to replicas as they are generated. 37 This can degrade replication performance because the various participating 38 environments must handle a fair amount of network I/O activity. 39 </p> 40 <p> 41 You can alleviate this problem by configuring your master environment for bulk 42 transfers. Bulk transfers simply cause replication messages to accumulate in a 43 buffer until a triggering event occurs. When this event occurs, the entire 44 contents of the buffer is sent to the replica, thereby eliminating excessive 45 network I/O. 46 </p> 47 <p> 48 Note that if you are using replica to replica transfers, then you might want any 49 replica that can service replication requests to also be configured for bulk 50 transfers. 51 </p> 52 <p> 53 The events that result in a bulk transfer of replication messages to a replica 54 will differ depending on if the transmitting environment is a master or a 55 replica. 56 </p> 57 <p> 58 If the servicing environment is a master environment, then bulk transfer 59 occurs when: 60 </p> 61 <div class="orderedlist"> 62 <ol type="1"> 63 <li> 64 <p> 65 Bulk transfers are configured for the master environment, and 66 </p> 67 </li> 68 <li> 69 <p> 70 the message buffer is full or 71 </p> 72 </li> 73 <li> 74 <p> 75 a permanent record (for example, a transaction commit or a 76 checkpoint record) is placed in the buffer for the replica. 77 </p> 78 </li> 79 </ol> 80 </div> 81 <p> 82 If the servicing environment is a replica environment (that is, replica to replica 83 transfers are in use), then a bulk transfer occurs when: 84 </p> 85 <div class="orderedlist"> 86 <ol type="1"> 87 <li> 88 <p> 89 Bulk transfers are configured for the transmitting replica, and 90 </p> 91 </li> 92 <li> 93 <p> 94 the message buffer is full or 95 </p> 96 </li> 97 <li> 98 <p> 99 the replica servicing the request is able to completely satisfy 100 the request with the contents of the message buffer. 101 </p> 102 </li> 103 </ol> 104 </div> 105 <p> 106 To configure bulk transfers, specify 107 108 <span> 109 <code class="literal">DB_REP_CONF_BULK</code> to 110 <code class="methodname">DB_ENV->rep_set_config()</code> 111 112 and then specify <code class="literal">1</code> to the <code class="literal">onoff</code> 113 parameter. (Specify <code class="literal">0</code> to turn the feature off.) 114 </span> 115 116 </p> 117 </div> 118 <div class="navfooter"> 119 <hr /> 120 <table width="100%" summary="Navigation footer"> 121 <tr> 122 <td width="40%" align="left"><a accesskey="p" href="c2ctransfer.html">Prev</a> </td> 123 <td width="20%" align="center"> 124 <a accesskey="u" href="addfeatures.html">Up</a> 125 </td> 126 <td width="40%" align="right"> </td> 127 </tr> 128 <tr> 129 <td width="40%" align="left" valign="top">Client to Client Transfer </td> 130 <td width="20%" align="center"> 131 <a accesskey="h" href="index.html">Home</a> 132 </td> 133 <td width="40%" align="right" valign="top"> </td> 134 </tr> 135 </table> 136 </div> 137 </body> 138</html> 139