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authorcoreyg <coreyg@13f79535-47bb-0310-9956-ffa450edef68>2014-11-21 09:30:19 +0000
committercoreyg <coreyg@13f79535-47bb-0310-9956-ffa450edef68>2014-11-21 09:30:19 +0000
commit200a40b332420f94992eb39a6d0ea1cf1490ffc4 (patch)
tree1c76ef1d254c7bfc91128a313d319bd60da9d01e /site/trunk/site-publish/rdb-das-c-partialupdate.html
parent85f53ab6ab4f664d63774c94b672a875c9e52b8a (diff)
Adding tuscany's website to their svn repo for svnpubsub
git-svn-id: http://svn.us.apache.org/repos/asf/tuscany@1640879 13f79535-47bb-0310-9956-ffa450edef68
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+<!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>
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+ <A href="http://incubator.apache.org/tuscany/"><IMG src="http://incubator.apache.org/tuscany/images/TuscanyLogo.jpg" border="0"></A>
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+ <IMG src="http://incubator.apache.org/tuscany/images/apache-incubator-logo.png" border="0">
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+ <TD align="left" valign="middle" class="topBarDiv" nowrap="true" width="100%">
+ &nbsp;<A href="home.html" title="Apache Tuscany">Apache Tuscany</A>&nbsp;&gt;&nbsp;<A href="home.html" title="Home">Home</A>&nbsp;&gt;&nbsp;<A href="das-overview.html" title="DAS Overview">DAS Overview</A>&nbsp;&gt;&nbsp;<A href="das-c.html" title="DAS C++">DAS C++</A>&nbsp;&gt;&nbsp;<A href="das-c-documentation-menu.html" title="DAS C++ Documentation Menu">DAS C++ Documentation Menu</A>&nbsp;&gt;&nbsp;<A href="rdb-das-c-user-guide.html" title="RDB DAS C++ - User Guide">RDB DAS C++ - User Guide</A>&nbsp;&gt;&nbsp;<A href="" title="RDB DAS C++ PartialUpdate">RDB DAS C++ PartialUpdate</A>
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+ <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>&nbsp;&nbsp;
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+ <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>
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