139 lines
5.5 KiB
HTML
139 lines
5.5 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="EVI maintenance" />
|
||
|
|
<meta name="abstract" content="There are unique challenges to maintaining EVIs. The following table shows a progression of how EVIs are maintained and the conditions under which EVIs are most effective and where EVIs are least effective based on the EVI maintenance characteristics." />
|
||
|
|
<meta name="description" content="There are unique challenges to maintaining EVIs. The following table shows a progression of how EVIs are maintained and the conditions under which EVIs are most effective and where EVIs are least effective based on the EVI maintenance characteristics." />
|
||
|
|
<meta name="DC.subject" content="index, encoded vector index maintenance, encoded vector index, maintenance" />
|
||
|
|
<meta name="keywords" content="index, encoded vector index maintenance, encoded vector index, maintenance" />
|
||
|
|
<meta name="DC.Relation" scheme="URI" content="whatareevi.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="evimaintenance" />
|
||
|
|
<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>EVI maintenance</title>
|
||
|
|
</head>
|
||
|
|
<body id="evimaintenance"><a name="evimaintenance"><!-- --></a>
|
||
|
|
<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
|
||
|
|
<h1 class="topictitle1">EVI maintenance</h1>
|
||
|
|
<div><p>There are unique challenges to maintaining EVIs. The following
|
||
|
|
table shows a progression of how EVIs are maintained and the conditions under
|
||
|
|
which EVIs are most effective and where EVIs are least effective based on
|
||
|
|
the EVI maintenance characteristics.</p>
|
||
|
|
|
||
|
|
<div class="tablenoborder"><table cellpadding="4" cellspacing="0" summary="" frame="border" border="1" rules="all"><caption>Table 1. EVI Maintenance Considerations</caption><thead align="left"><tr valign="bottom"><th valign="bottom" id="d0e30"> </th>
|
||
|
|
<th valign="bottom" id="d0e31">Condition</th>
|
||
|
|
<th valign="bottom" id="d0e33">Characteristics</th>
|
||
|
|
</tr>
|
||
|
|
</thead>
|
||
|
|
<tbody><tr><td rowspan="4" valign="top" headers="d0e30 "><p></p>
|
||
|
|
Most Effective <p><br />
|
||
|
|
<br />
|
||
|
|
<br />
|
||
|
|
<br />
|
||
|
|
<br />
|
||
|
|
<br />
|
||
|
|
<br />
|
||
|
|
<br />
|
||
|
|
<br />
|
||
|
|
<br />
|
||
|
|
<br />
|
||
|
|
<br />
|
||
|
|
<br />
|
||
|
|
<br />
|
||
|
|
<br />
|
||
|
|
<br />
|
||
|
|
<br />
|
||
|
|
<br />
|
||
|
|
<br />
|
||
|
|
<br />
|
||
|
|
<br />
|
||
|
|
<br />
|
||
|
|
<br />
|
||
|
|
</p>
|
||
|
|
<img src="rzajq501.gif" alt="Arrow pointing down" /><p><br />
|
||
|
|
<br />
|
||
|
|
<br />
|
||
|
|
<br />
|
||
|
|
<br />
|
||
|
|
<br />
|
||
|
|
<br />
|
||
|
|
<br />
|
||
|
|
<br />
|
||
|
|
<br />
|
||
|
|
<br />
|
||
|
|
<br />
|
||
|
|
<br />
|
||
|
|
<br />
|
||
|
|
<br />
|
||
|
|
<br />
|
||
|
|
<br />
|
||
|
|
<br />
|
||
|
|
<br />
|
||
|
|
<br />
|
||
|
|
<br />
|
||
|
|
<br />
|
||
|
|
</p>
|
||
|
|
Least Effective</td>
|
||
|
|
<td valign="top" headers="d0e31 ">When inserting an existing distinct key value</td>
|
||
|
|
<td valign="top" headers="d0e33 "><ul><li>Minimum overhead</li>
|
||
|
|
<li>Symbol table key value looked up and statistics updated</li>
|
||
|
|
<li>Vector element added for new row, with existing byte code</li>
|
||
|
|
</ul>
|
||
|
|
</td>
|
||
|
|
</tr>
|
||
|
|
<tr><td valign="top" headers="d0e31 ">When inserting a <em>new</em> distinct key value - in
|
||
|
|
order, within byte code range</td>
|
||
|
|
<td valign="top" headers="d0e33 "><ul><li>Minimum overhead</li>
|
||
|
|
<li>Symbol table key value added, byte code assigned, statistics assigned</li>
|
||
|
|
<li>Vector element added for new row, with new byte code</li>
|
||
|
|
</ul>
|
||
|
|
</td>
|
||
|
|
</tr>
|
||
|
|
<tr><td valign="top" headers="d0e31 ">When inserting a new distinct key value - out of order,
|
||
|
|
within byte code range</td>
|
||
|
|
<td valign="top" headers="d0e33 "><ul><li>Minimum overhead if contained within overflow area threshold</li>
|
||
|
|
<li>Symbol table key value added to overflow area, byte code assigned, statistics
|
||
|
|
assigned</li>
|
||
|
|
<li>Vector element added for new row, with new byte code</li>
|
||
|
|
<li>Considerable overhead if overflow area threshold reached</li>
|
||
|
|
<li>Access path validated - not available</li>
|
||
|
|
<li>EVI refreshed, overflow area keys incorporated, new byte codes assigned
|
||
|
|
(symbol table and vector elements updated)</li>
|
||
|
|
</ul>
|
||
|
|
</td>
|
||
|
|
</tr>
|
||
|
|
<tr><td valign="top" headers="d0e31 ">When inserting a new distinct key value - out of byte
|
||
|
|
code range</td>
|
||
|
|
<td valign="top" headers="d0e33 "><ul><li>Considerable overhead</li>
|
||
|
|
<li>Access plan invalidated - not available</li>
|
||
|
|
<li>EVI refreshed, next byte code size used, new byte codes assigned (symbol
|
||
|
|
table and vector elements updated</li>
|
||
|
|
</ul>
|
||
|
|
</td>
|
||
|
|
</tr>
|
||
|
|
</tbody>
|
||
|
|
</table>
|
||
|
|
</div>
|
||
|
|
</div>
|
||
|
|
<div>
|
||
|
|
<div class="familylinks">
|
||
|
|
<div class="parentlink"><strong>Parent topic:</strong> <a href="whatareevi.htm" title="An encoded vector index (EVI) is an index object that is used by the query optimizer and database engine to provide fast data access in decision support and query reporting environments.">Encoded vector indexes</a></div>
|
||
|
|
</div>
|
||
|
|
</div>
|
||
|
|
</body>
|
||
|
|
</html>
|