57 lines
4.2 KiB
HTML
57 lines
4.2 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="concept" />
|
||
|
|
<meta name="DC.Title" content="General index maintenance" />
|
||
|
|
<meta name="abstract" content="Whenever indexes are created and used, there is a potential for a decrease in I/O velocity due to maintenance, therefore, you should consider the maintenance cost of creating and using additional indexes. For radix indexes with MAINT(*IMMED) maintenance occurs when inserting, updating or deleting rows." />
|
||
|
|
<meta name="description" content="Whenever indexes are created and used, there is a potential for a decrease in I/O velocity due to maintenance, therefore, you should consider the maintenance cost of creating and using additional indexes. For radix indexes with MAINT(*IMMED) maintenance occurs when inserting, updating or deleting rows." />
|
||
|
|
<meta name="DC.subject" content="index, maintenance" />
|
||
|
|
<meta name="keywords" content="index, maintenance" />
|
||
|
|
<meta name="DC.Relation" scheme="URI" content="rzajqbinary.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="genidxmaint" />
|
||
|
|
<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>General index maintenance</title>
|
||
|
|
</head>
|
||
|
|
<body id="genidxmaint"><a name="genidxmaint"><!-- --></a>
|
||
|
|
<img src="./delta.gif" alt="Start of change" /><!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
|
||
|
|
<h1 class="topictitle1">General index maintenance</h1>
|
||
|
|
<div><p>Whenever indexes are created and used, there is a potential for
|
||
|
|
a decrease in I/O velocity due to maintenance, therefore, you should consider
|
||
|
|
the maintenance cost of creating and using additional indexes. For radix indexes
|
||
|
|
with MAINT(*IMMED) maintenance occurs when inserting, updating or deleting
|
||
|
|
rows.</p>
|
||
|
|
<p>To reduce the maintenance of your indexes consider: </p>
|
||
|
|
<ul><li>Minimizing the number of indexes over a given table by creating composite
|
||
|
|
(multiple column) key indexes such that an index can be used for multiple
|
||
|
|
different situations.</li>
|
||
|
|
<li>Dropping indexes during batch inserts, updates, and deletes</li>
|
||
|
|
<li>Creating in parallel. Either create indexes, one at a time, in parallel
|
||
|
|
using SMP or create multiple indexes simultaneously with multiple batch jobs</li>
|
||
|
|
<li>Maintaining indexes in parallel using SMP</li>
|
||
|
|
</ul>
|
||
|
|
<p>The goal of creating indexes is to improve query performance by providing
|
||
|
|
statistics and implementation choices, while maintaining a reasonable balance
|
||
|
|
on the number of indexes so as to limit maintenance overhead</p>
|
||
|
|
</div>
|
||
|
|
<div>
|
||
|
|
<div class="familylinks">
|
||
|
|
<div class="parentlink"><strong>Parent topic:</strong> <a href="rzajqbinary.htm" title="A radix index is a multilevel, hybrid tree structure that allows a large number of key values to be stored efficiently while minimizing access times. A key compression algorithm assists in this process. The lowest level of the tree contains the leaf nodes, which contain the address of the rows in the base table that are associated with the key value. The key value is used to quickly navigator to the leaf node with a few simple binary search tests.">Binary radix indexes</a></div>
|
||
|
|
</div>
|
||
|
|
</div>
|
||
|
|
<img src="./deltaend.gif" alt="End of change" /></body>
|
||
|
|
</html>
|