63 lines
3.7 KiB
HTML
63 lines
3.7 KiB
HTML
|
<?xml version="1.0" encoding="UTF-8"?>
|
||
|
|
<!DOCTYPE html
|
||
|
|
PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||
|
|
<html lang="en-us" xml:lang="en-us">
|
||
|
|
<head>
|
||
|
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
|
||
|
|
<meta name="security" content="public" />
|
||
|
|
<meta name="Robots" content="index,follow" />
|
||
|
|
<meta http-equiv="PICS-Label" content='(PICS-1.1 "http://www.icra.org/ratingsv02.html" l gen true r (cz 1 lz 1 nz 1 oz 1 vz 1) "http://www.rsac.org/ratingsv01.html" l gen true r (n 0 s 0 v 0 l 0) "http://www.classify.org/safesurf/" l gen true r (SS~~000 1))' />
|
||
|
|
<meta name="DC.Type" content="reference" />
|
||
|
|
<meta name="DC.Title" content="SQL402A - Hashing algorithm used to process join" />
|
||
|
|
<meta name="DC.Relation" scheme="URI" content="prtsqlinfmsg.htm" />
|
||
|
|
<meta name="copyright" content="(C) Copyright IBM Corporation 1998, 2006" />
|
||
|
|
<meta name="DC.Rights.Owner" content="(C) Copyright IBM Corporation 1998, 2006" />
|
||
|
|
<meta name="DC.Format" content="XHTML" />
|
||
|
|
<meta name="DC.Identifier" content="sql402a" />
|
||
|
|
<meta name="DC.Language" content="en-us" />
|
||
|
|
<!-- All rights reserved. Licensed Materials Property of IBM -->
|
||
|
|
<!-- US Government Users Restricted Rights -->
|
||
|
|
<!-- Use, duplication or disclosure restricted by -->
|
||
|
|
<!-- GSA ADP Schedule Contract with IBM Corp. -->
|
||
|
|
<link rel="stylesheet" type="text/css" href="./ibmdita.css" />
|
||
|
|
<link rel="stylesheet" type="text/css" href="./ic.css" />
|
||
|
|
<title>SQL402A - Hashing algorithm used to process join</title>
|
||
|
|
</head>
|
||
|
|
<body id="sql402a"><a name="sql402a"><!-- --></a>
|
||
|
|
<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
|
||
|
|
<h1 class="topictitle1">SQL402A - Hashing algorithm used to process join</h1>
|
||
|
|
<div>
|
||
|
|
<div class="tablenoborder"><table cellpadding="4" cellspacing="0" summary="" frame="border" border="1" rules="all"><thead align="left"><tr><th colspan="2" align="center" valign="middle" id="d0e16">SQL402A</th>
|
||
|
|
</tr>
|
||
|
|
</thead>
|
||
|
|
<tbody><tr valign="middle"><td valign="middle" width="26.02040816326531%" headers="d0e16 ">Message Text:</td>
|
||
|
|
<td valign="middle" width="73.9795918367347%" headers="d0e16 ">Hashing algorithm used to process join</td>
|
||
|
|
</tr>
|
||
|
|
<tr valign="middle"><td valign="middle" width="26.02040816326531%" headers="d0e16 ">Cause Text:</td>
|
||
|
|
<td valign="middle" width="73.9795918367347%" headers="d0e16 ">The hash join algorithm is typically used for longer running join queries.
|
||
|
|
The original query will be subdivided into hash join steps. <p></p>
|
||
|
|
Each
|
||
|
|
hash join step will be optimized and processed separately. Access plan implementation
|
||
|
|
information for each of the hash join steps is not available because access
|
||
|
|
plans are not saved for the individual hash join dials. Debug messages detailing
|
||
|
|
the implementation of each hash dial can be found in the joblog if the query
|
||
|
|
is run in debug mode using the <span class="cmdname">STRDBG</span> CL command.</td>
|
||
|
|
</tr>
|
||
|
|
<tr valign="middle"><td valign="middle" width="26.02040816326531%" headers="d0e16 ">Recovery Text:</td>
|
||
|
|
<td valign="middle" width="73.9795918367347%" headers="d0e16 ">The hash join method is usually a good implementation choice, however,
|
||
|
|
if you want to disallow the use of this method specify ALWCPYDTA(*YES).
|
||
|
|
<p></p>
|
||
|
|
Refer to <a href="rzajqdta.htm#rzajqdta">Data access on DB2 UDB for iSeries: data access paths and methods</a> for more
|
||
|
|
information about hashing algorithm for join processing.</td>
|
||
|
|
</tr>
|
||
|
|
</tbody>
|
||
|
|
</table>
|
||
|
|
</div>
|
||
|
|
</div>
|
||
|
|
<div>
|
||
|
|
<div class="familylinks">
|
||
|
|
<div class="parentlink"><strong>Parent topic:</strong> <a href="prtsqlinfmsg.htm" title="The following are the messages returned from PRTSQLINF.">PRTSQLINF message reference</a></div>
|
||
|
|
</div>
|
||
|
|
</div>
|
||
|
|
</body>
|
||
|
|
</html>
|