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diff --git a/site/trunk/site-publish/rdb-das-c-partialupdate.html b/site/trunk/site-publish/rdb-das-c-partialupdate.html new file mode 100644 index 0000000000..26e87d10cc --- /dev/null +++ b/site/trunk/site-publish/rdb-das-c-partialupdate.html @@ -0,0 +1,92 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> +<HTML> + <HEAD> + <LINK type="text/css" rel="stylesheet" href="http://incubator.apache.org/tuscany/stylesheets/default.css"> + <LINK rel="SHORTCUT ICON" href="http://cwiki.apache.org/confluence/pages/$images/favicon.ico"> + <TITLE>RDB DAS C++ PartialUpdate : Apache Tuscany</TITLE> + <META http-equiv="Content-Type" content="text/html;charset=UTF-8"></HEAD> + + <BODY onload="init()"> + + <TABLE valign="top" border="0" cellspacing="0" cellpadding="0" width="100%" background="http://incubator.apache.org/tuscany/images/TuscanyLogoNEW_Text_120px_bg.jpg"> + <TR> + <TD valing="top" align="left"> + <A href="http://cwiki.apache.org/confluence/pages/$siteroot"><IMG src="http://incubator.apache.org/tuscany/images/TuscanyLogoNEW_Text_120px_bg.jpg" height="91" width="25" border="0"></A> + </TD> + <TD> + <A href="http://incubator.apache.org/tuscany/"><IMG src="http://incubator.apache.org/tuscany/images/TuscanyLogo.jpg" border="0"></A> + </TD> + + <TD width="100%"> + + </TD> + <TD align="right"> + <IMG src="http://incubator.apache.org/tuscany/images/apache-incubator-logo.png" border="0"> + </TD> + + <!-- Adds the edit page link to the top banner--> + <TD valign="bottom"> + <DIV style="padding: 2px 10px; margin: 0px;"> + <A href="http://cwiki.apache.org/confluence/pages/editpage.action?pageId=69449"> + <IMG src="http://incubator.apache.org/tuscany/images/notep_16.gif" height="16" width="16" border="0" align="absmiddle" title="Edit Page"></A> + </DIV> + </TD> + + </TR> + </TABLE> + + <TABLE border="0" cellpadding="2" cellspacing="0" width="100%"> + <TR class="topBar"> + <TD align="left" valign="middle" class="topBarDiv" nowrap="true" width="100%"> + <A href="home.html" title="Apache Tuscany">Apache Tuscany</A> > <A href="home.html" title="Home">Home</A> > <A href="das-overview.html" title="DAS Overview">DAS Overview</A> > <A href="das-c.html" title="DAS C++">DAS C++</A> > <A href="das-c-documentation-menu.html" title="DAS C++ Documentation Menu">DAS C++ Documentation Menu</A> > <A href="rdb-das-c-user-guide.html" title="RDB DAS C++ - User Guide">RDB DAS C++ - User Guide</A> > <A href="" title="RDB DAS C++ PartialUpdate">RDB DAS C++ PartialUpdate</A> + </TD> + + <TD align="left" valign="middle" class="topBarDiv" nowrap="true"> + <A href="http://mail-archives.apache.org/mod_mbox/ws-tuscany-user">User List</A> | <A href="http://mail-archives.apache.org/mod_mbox/ws-tuscany-dev">Dev List</A> | <A href="http://issues.apache.org/jira/browse/Tuscany">Issue Tracker</A> + </TD> + </TR> + </TABLE> + + <TABLE border="0" cellpadding="0" width="100%" bgcolor="#FFFFFF"> + <TR> + <TD align="left" valign="top"> + <DIV id="PageContent"> + + <DIV class="pagecontent"> + <DIV class="wiki-content"> + <H1><A name="RDBDASC%2B%2BPartialUpdate-PartialUpdate"></A>PartialUpdate</H1> + +<P>The RDB DAS uses the SDO Change Summary to generate a set of database write operations. Rather than generated a statement to update all columns in a table that maps to a SDO DataObject Type, the DAS generates statements that update ony those columns that map to a modified DataObject property. For example, consider a Customer DataObject that has had the LastName property changed. The <B>partial update</B> statement generated by the DAS will look something like this:</P> +<DIV class="preformatted"><DIV class="preformattedContent"> +<PRE>UPDATE CUSTOMER SET LASTNAME = 'Tuscany' WHERE ID = '1' +</PRE> +</DIV></DIV> +<P>Rather than a statement that updates all columns like this:</P> +<DIV class="preformatted"><DIV class="preformattedContent"> +<PRE>UPDATE CUSTOMER SET FIRSTNAME = 'APACHE', SET LASTNAME = 'TUSCANY', SET ADDRESS = 'USA', SET PHONE = '555-5555', SET AGE = '7', SET SHOESIZE = '15' WHERE ID = '1' +</PRE> +</DIV></DIV> +<P>There are a couple of very good reasons for using a partial update approach. For one, a performance boost can be realized by applications writing to wide tables. For example, tables with over 100 columns are not unheard of. It can be a huge waste of resource to update 100 columns when only one was modified. Another reason for partial update is that some databases employ <SPAN class="nobr"><A href="http://en.wikipedia.org/wiki/Database_trigger" title="Visit page outside Confluence" rel="nofollow">triggers<SUP><IMG class="rendericon" src="http://cwiki.apache.org/confluence/images/icons/linkext7.gif" height="7" width="7" align="absmiddle" alt="" border="0"></SUP></A></SPAN>on specific columns in a table. Partial updates are necessary when column triggers are employed to avoid tripping the trigger on every row update rather than only on updates to the specific column. </P> + </DIV> + </DIV> + </DIV> + </TD> + </TR> + </TABLE> + + <SCRIPT src="http://www.google-analytics.com/urchin.js" type="text/javascript"> + </SCRIPT> + <SCRIPT type="text/javascript"> + _uacct = "UA-1174707-5"; + urchinTracker(); + </SCRIPT> + + <A href="http://www.statcounter.com/" target="_blank"><IMG src="http://c26.statcounter.com/counter.php?sc_project=2619156&java=0&security=94bd7e7d&invisible=0" alt="website stats" border="0"></A> + + <DIV class="footer"> + Copyright © 2003-2007, The Apache Software Foundation + </DIV> + + </BODY> +</HTML>
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