blob: f8d85e8ffce232f9e58c3bd1326fae18a69875a8 [file] [log] [blame]
<!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 Oracle Extensions for Queries | EclipseLink 2.5.x Understanding EclipseLink</title>
<meta name="generator" content="Oracle DARB XHTML Converter (Mode = document) - Version 1.0.17" />
<meta name="date" content="2013-10-03T10:37:16Z" />
<meta name="robots" content="noarchive" />
<meta name="doctitle" content="About Oracle Extensions for Queries" />
<meta name="relnum" content="2.5" />
<link rel="stylesheet" type="text/css" href="../../dcommon/style.css" media="screen" />
<link rel="copyright" href="../../dcommon/html/cpyr.htm" title="Copyright" type="text/html" />
<link rel="start" href="../../index.htm" title="Home" type="text/html" />
<link rel="contents" href="toc.htm" title="Contents" type="text/html" />
<link rel="prev" href="queries008.htm" title="Previous" type="text/html" />
<link rel="next" href="expressions.htm" title="Next" type="text/html" />
<!-- START: Disqus --><script type="text/javascript"> var disqus_developer = 0; </script><!-- END: Disqus --><!-- START: Sharethis --><script type="text/javascript">var switchTo5x=true;</script><script type="text/javascript" src="http://w.sharethis.com/button/buttons.js"></script><script type="text/javascript" src="http://s.sharethis.com/loader.js"></script> <!-- END: Sharethis --></head>
<body bgcolor="#FFFFFF"><iframe id="docheader" frameborder="0" framemargin="0" scrolling="no" src="../../dcommon/header.html"></iframe><script src="http://www.google.com/jsapi" type="text/javascript"></script><script type="text/javascript"> google.load('search', '1', {language : 'en'}); google.setOnLoadCallback(function() { var customSearchOptions = {}; var googleAnalyticsOptions = {}; googleAnalyticsOptions['queryParameter'] = 'q'; googleAnalyticsOptions['categoryParameter'] = ''; customSearchOptions['googleAnalyticsOptions'] = googleAnalyticsOptions; var customSearchControl = new google.search.CustomSearchControl( '016171230611334810008:mdbgdwjv8zu', customSearchOptions); customSearchControl.setResultSetSize(google.search.Search.FILTERED_CSE_RESULTSET); var options = new google.search.DrawOptions(); options.setSearchFormRoot('cse-search-form'); customSearchControl.draw('cse', options); }, true);</script><link rel="stylesheet" href="http://www.google.com/cse/style/look/default.css" type="text/css" /><div id="cse" style="width:100%;"></div>
<div class="header"><a id="top" name="top"></a>
<table class="simple oac_no_warn" summary="" cellspacing="0" cellpadding="0" width="100%">
<tr>
<td align="left" valign="top"><div class="booktitle">Understanding EclipseLink,
<b>2.5</b><br /></font></td>
<td valign="bottom" align="right" width="144">
<table class="simple oac_no_warn" summary="" cellspacing="0" cellpadding="0" width="100%">
<tr>
<td>&nbsp;</td>
<td align="center" valign="top"><a href="toc.htm"><img src="../../dcommon/images/contents.png" alt="Go To Table Of Contents" border="0" height="16" width="16" /><br />
</td><td>&nbsp;</td><td align="center"><a href="../../" target="_top" class="external text" title="Search" rel="nofollow"><img src="../../dcommon/images/search.png" alt="Search" style="border:0;" /><br /><span class="mini"></span></a></td><td>&nbsp;</td><td align="center"><a href="../eclipselink_otlcg.pdf" title="PDF" target="_blank"><img src="../../dcommon/images/pdf_icon.png" style="padding-right:5px;border:0" alt="PDF"></a></td>
</tr>
</table>
</td>
</tr>
</table>
<hr />
<table class="navigation simple oac_no_warn" summary="" cellspacing="0" cellpadding="0" width="100" align="center">
<tr>
<td align="center"><a href="queries008.htm"><img src="../../dcommon/images/larrow.png" alt="Previous" border="0" height="16" width="16" /></a></td>
<td align="center"><a href="expressions.htm"><img src="../../dcommon/images/rarrow.png" alt="Next" border="0" height="16" width="16" /></a></td>
<td>&nbsp;</td>
</tr>
</table>
</div>
<!-- class="header" -->
<div class="ind"><!-- End Header --><a id="CACHGGDB" name="CACHGGDB"></a><a id="OTLCG94063" name="OTLCG94063"></a>
<div class="sect1"><!-- infolevel="all" infotype="General" -->
<h1 class="sect1"><font face="arial, helvetica, sans-serif" color="#330099">About Oracle Extensions for Queries</font></h1>
<p>When you use EclipseLink with Oracle Database, you can make use of the following Oracle-specific query features from within your EclipseLink applications:</p>
<ul>
<li>
<p><a href="#CACJAJFH">Query Hints</a></p>
</li>
<li>
<p><a href="#CACDIJHF">Hierarchical Queries</a></p>
</li>
<li>
<p><a href="#CACCJIGE">Flashback Queries</a></p>
</li>
<li>
<p><a href="#CACDDIDI">Stored Functions</a></p>
</li>
</ul>
<a id="CACJAJFH" name="CACJAJFH"></a><a id="OTLCG94064" name="OTLCG94064"></a>
<div class="sect2"><!-- infolevel="all" infotype="General" -->
<h2 class="sect2"><font face="arial, helvetica, sans-serif" color="#330099">Query Hints</font></h2>
<p>Oracle lets you specify SQL query additions called hints that can influence how the database server SQL optimizer works. This lets you influence decisions usually reserved for the optimizer. You use hints to specify things such as join order for a join statement, or the optimization approach for a SQL call.</p>
<p>You specify hints using the <code>DatabaseQuery</code> method <code>setHintString</code>.</p>
<p>For more information, see the performance tuning guide for your database.</p>
</div>
<!-- class="sect2" -->
<a id="CACDIJHF" name="CACDIJHF"></a><a id="OTLCG94065" name="OTLCG94065"></a>
<div class="sect2"><!-- infolevel="all" infotype="General" -->
<h2 class="sect2"><font face="arial, helvetica, sans-serif" color="#330099">Hierarchical Queries</font></h2>
<p>Oracle Database Hierarchical Queries mechanism lets you select database rows based on hierarchical order. For example, you can design a query that reads the row of a given employee, followed by the rows of people the employee manages, followed by their managed employees, and so on.</p>
<p>You specify a hierarchical query clause using <code>DatabaseQuery</code> subclass <code>ReadAllQuery</code> method <code>setHierarchicalQueryClause</code>.</p>
</div>
<!-- class="sect2" -->
<a id="CACCJIGE" name="CACCJIGE"></a><a id="OTLCG94066" name="OTLCG94066"></a>
<div class="sect2"><!-- infolevel="all" infotype="General" -->
<h2 class="sect2"><font face="arial, helvetica, sans-serif" color="#330099">Flashback Queries</font></h2>
<p>When using EclipseLink with Oracle9<em>i</em> Database (or later), you can acquire a special historical session where all objects are read as of a past time, and then you can express read queries depending on how your objects are changing over time.</p>
</div>
<!-- class="sect2" -->
<a id="CACDDIDI" name="CACDDIDI"></a><a id="OTLCG94067" name="OTLCG94067"></a>
<div class="sect2"><!-- infolevel="all" infotype="General" -->
<h2 class="sect2"><font face="arial, helvetica, sans-serif" color="#330099">Stored Functions</font></h2>
<p>A stored function is an Oracle Database mechanism that provides all the capabilities of a stored procedure in addition to returning a value.</p>
</div>
<!-- class="sect2" --></div>
<!-- class="sect1" --></div>
<!-- class="ind" -->
<!-- Start Footer -->
<div class="footer">
<hr />
<table class="simple oac_no_warn" summary="" cellspacing="0" cellpadding="0" width="100%">
<col width="33%" />
<col width="*" />
<col width="33%" />
<tr>
<td valign="bottom">
<table class="navigation simple oac_no_warn" summary="" cellspacing="0" cellpadding="0" width="100" align="center">
<col width="*" />
<col width="48%" />
<col width="48%" />
<tr>
<td>&nbsp;</td>
<td align="center"><a href="queries008.htm"><img src="../../dcommon/images/larrow.png" alt="Previous" border="0" height="16" width="16" /></a></td>
<td align="center"><a href="expressions.htm"><img src="../../dcommon/images/rarrow.png" alt="Next" border="0" height="16" width="16" /></a></td>
</tr>
</table>
</td>
<td align="center" width="34%"><a href="http://www.eclipse.org/eclipselink/" title="EclipseLink home"><img src="../../dcommon/images/ellogo.png" alt="EclipseLink" width="150" border="0" /></a><br />
<td valign="bottom" align="right">
<table class="simple oac_no_warn" summary="" cellspacing="0" cellpadding="0" width="225">
<tr>
<td>&nbsp;</td>
<td align="center" valign="top"><a href="toc.htm"><img src="../../dcommon/images/contents.png" alt="Go To Table Of Contents" border="0" height="16" width="16" /><br />
</td><td>&nbsp;</td><td align="center"><a href="../../" target="_top" class="external text" title="Search" rel="nofollow"><img src="../../dcommon/images/search.png" alt="Search" style="border:0;" /><br /><span class="mini"></span></a></td><td>&nbsp;</td><td align="center"><a href="../eclipselink_otlcg.pdf" title="PDF" target="_blank"><img src="../../dcommon/images/pdf_icon.png" style="padding-right:5px;border:0" alt="PDF"></a></td>
</tr>
</table>
</td>
</tr>
</table>
</div>
<!-- class="footer" -->
<div id="copyright">Copyright &copy; 2012 by The Eclipse Foundation under the <a href="http://www.eclipse.org/org/documents/epl-v10.php">Eclipse Public License (EPL)</a><br /> <script type="text/javascript">var LastUpdated = document.lastModified;document.writeln ("Updated: " + LastUpdated);</script> </div><!-- START: Analytics --><script type="text/javascript"> var _gaq = _gaq || []; _gaq.push(['_setAccount', 'UA-1608008-2']); _gaq.push(['_trackPageview']); (function() { var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true; ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s); })(); </script><!-- END: Analytics --><!-- START: Sharethis --><script>var options={ "publisher": "e2fe9e07-fab6-4f84-83ea-0991b429842c", "position": "right", "ad": { "visible": false, "openDelay": 5, "closeDelay": 0}};var st_hover_widget = new sharethis.widgets.hoverbuttons(options);</script><!-- END: Sharethis --></body>
</html>