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<!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" xml:lang="en" lang="en"> <head> <meta http-equiv="Content-Type" content="text/html; charset=us-ascii" /> <meta http-equiv="Content-Style-Type" content="text/css" /> <meta http-equiv="Content-Script-Type" content="text/javascript" /> <title>About Change Capture with a Capture Process</title> <meta name="generator" content="Oracle DARB XHTML Converter (Mode = ohj/ohw) - Version 5.1.1 Build 005" /> <meta name="date" content="2009-06-04T17:1:1Z" /> <meta name="robots" content="noarchive" /> <meta name="doctitle" content="About Change Capture with a Capture Process" /> <meta name="relnum" content="11g Release 2 (11.2)" /> <meta name="partnum" content="E10703-01" /> <link rel="copyright" href="./dcommon/html/cpyr.htm" title="Copyright" type="text/html" /> <link rel="stylesheet" href="./dcommon/css/blafdoc.css" title="Oracle BLAFDoc" type="text/css" /> <link rel="contents" href="toc.htm" title="Contents" type="text/html" /> <link rel="prev" href="tdpii_repcont002.htm" title="Previous" type="text/html" /> <link rel="next" href="tdpii_repcont004.htm" title="Next" type="text/html" /> <script src="./callback.js" type="text/javascript"></script> <noscript>Your browser does not support JavaScript. This help page requires JavaScript to render correctly.</noscript> </head> <body> <div class="zz-skip-header"><a href="#BEGIN">Skip Headers</a></div> <table class="simple oac_no_warn" summary="" cellspacing="0" cellpadding="0" width="100%"> <col width="86%" /> <col width="*" /> <tr valign="bottom"> <td align="left"></td> <td align="center"><a href="tdpii_repcont002.htm"><img src="./dcommon/gifs/leftnav.gif" alt="Previous" /><br /> <span class="icon">Previous</span></a> </td> <td align="center"><a href="tdpii_repcont004.htm"><img src="./dcommon/gifs/rightnav.gif" alt="Next" /><br /> <span class="icon">Next</span></a></td> </tr> </table> <p><a id="BABBFECB" name="BABBFECB"></a><a id="TDPII068" name="TDPII068"></a></p> <div class="sect3"><!-- infolevel="all" infotype="General" --> <h1>About Change Capture with a Capture Process<a id="sthref102" name="sthref102"></a><a id="sthref103" name="sthref103"></a><a id="sthref104" name="sthref104"></a><a id="sthref105" name="sthref105"></a><a id="sthref106" name="sthref106"></a></h1> <a name="BEGIN" id="BEGIN"></a> <p>A <span class="bold">capture process</span> is an optional Oracle Database background process that asynchronously captures changes recorded in the redo log. When a capture process captures a database change, it converts it into a logical change record (LCR) and enqueues the LCR.</p> <p>A capture process is always associated with a single queue, and it enqueues LCRs into this queue only. For improved performance, captured LCRs are always stored in a <span class="bold">buffered queue</span>, which is System Global Area (SGA) memory associated with a queue.</p> <p><a href="#BABGECJA">Figure: Capture Process</a> shows how a capture process works.</p> <div class="figure"><a id="BABGECJA" name="BABGECJA"></a><a id="TDPII219" name="TDPII219"></a> <p class="titleinfigure">Capture Process</p> <img src="img/tdpii012.gif" alt="Description of this figure follows" title="Description of this figure follows" longdesc="img_text/tdpii012.htm" /><br /> <a id="sthref107" name="sthref107" href="img_text/tdpii012.htm">Description of "Capture Process"</a><br /> <br /></div> <!-- class="figure" --> <p><a id="sthref108" name="sthref108"></a><a id="sthref109" name="sthref109"></a>A capture process can run on the source database or on a remote database. When a capture process runs on the source database, the capture process is called a <span class="bold">local capture process</span>. When a capture process runs on a remote database, the capture process is called a <span class="bold">downstream capture process</span>.</p> <p>With downstream capture, redo transport services use the log writer process (LGWR) at the source database to send redo data to the database that runs the downstream capture process. A downstream capture process requires fewer resources at the source database because a different database captures the changes. A local capture process, however, is easier to configure and manage than a downstream capture process. Local capture processes also provide more flexibility in replication environments with different platforms or different versions of Oracle Database.</p> <div class="helpinfonotealso"> <h2>Related Topics</h2> <p><a href="tdpii_repcont022.htm#BABIJCDG">Tutorial: Configuring Two-Database Replication with a Downstream Capture Process</a></p> <p><a href="tdpii_repcont023.htm#BABBIBCD">Tutorial: Configuring Hub-and-Spoke Replication with Local Capture Processes</a></p> <p><a href="tdpii_adcont002.htm#CHDGHGBI">Managing Capture Processes</a></p> <p><a href="tdpii_adcont014.htm#CHDHEHGH">Monitoring Capture Processes</a></p> <p><a href="topicid:STRMS002">Oracle Streams Information Capture</a></p> <p><a href="topicid:ADMQS12049">About Online Redo Log Files</a></p> </div> </div> <!-- class="sect3" --> <!-- Start Footer --> <div class="footer"> <table class="simple oac_no_warn" summary="" cellspacing="0" cellpadding="0" width="100%"> <col width="86%" /> <col width="*" /> <tr> <td align="left"><span class="copyrightlogo">Copyright © 2007, 2009, Oracle and/or its affiliates. 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