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	<title>DBAlife &#187; 索引</title>
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	<description>网站系统架构实践</description>
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		<title>如何确定一个索引是否需要重建</title>
		<link>http://www.dbalife.com/archives/127.html</link>
		<comments>http://www.dbalife.com/archives/127.html#comments</comments>
		<pubDate>Fri, 30 May 2008 02:21:11 +0000</pubDate>
		<dc:creator>skywalker</dc:creator>
				<category><![CDATA[DB性能优化]]></category>
		<category><![CDATA[Oracle]]></category>
		<category><![CDATA[数据库管理]]></category>
		<category><![CDATA[if_rows]]></category>
		<category><![CDATA[index]]></category>
		<category><![CDATA[rebuild]]></category>
		<category><![CDATA[索引]]></category>
		<category><![CDATA[重建]]></category>

		<guid isPermaLink="false">http://www.dbalife.com/?p=127</guid>
		<description><![CDATA[首先分析索引 ANALYZE INDEX XXXXX VALIDATE STRUCTURE; 分析完成后会在index_stats视图中存放分析结果，从分析结果计算是否需要重建索引 select del_lf_rows/lf_rows from index_stats; 若结果大于0.2，则索引需要重建。 -EOF- Related posts: 模糊查询like '%XX%' 的优化一例 笔记：重建用户下所有索引 在线分析statspack报告
Related posts:<ol>
<li><a href='http://www.dbalife.com/archives/176.html' rel='bookmark' title='模糊查询like &#039;%XX%&#039; 的优化一例'>模糊查询like '%XX%' 的优化一例</a></li>
<li><a href='http://www.dbalife.com/archives/31.html' rel='bookmark' title='笔记：重建用户下所有索引'>笔记：重建用户下所有索引</a></li>
<li><a href='http://www.dbalife.com/archives/104.html' rel='bookmark' title='在线分析statspack报告'>在线分析statspack报告</a></li>
</ol>]]></description>
			<content:encoded><![CDATA[<p>首先分析索引</p>
<blockquote><p>ANALYZE INDEX  XXXXX  VALIDATE STRUCTURE;</p></blockquote>
<p>分析完成后会在index_stats视图中存放分析结果，从分析结果计算是否需要重建索引</p>
<blockquote><p>select del_lf_rows/lf_rows from index_stats;</p></blockquote>
<p>若结果大于0.2，则索引需要重建。</p>
<p>-EOF-</p>
<p>Related posts:<ol>
<li><a href='http://www.dbalife.com/archives/176.html' rel='bookmark' title='模糊查询like &#039;%XX%&#039; 的优化一例'>模糊查询like '%XX%' 的优化一例</a></li>
<li><a href='http://www.dbalife.com/archives/31.html' rel='bookmark' title='笔记：重建用户下所有索引'>笔记：重建用户下所有索引</a></li>
<li><a href='http://www.dbalife.com/archives/104.html' rel='bookmark' title='在线分析statspack报告'>在线分析statspack报告</a></li>
</ol></p>]]></content:encoded>
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