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	<title>SQL Server Planet &#187; Query Optimizer</title>
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	<description>Tips and Articles on SQL Server</description>
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		<title>User Defined Functions and Performance</title>
		<link>http://sqlserverplanet.com/query-optimizer/user-defined-functions-and-performance</link>
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		<pubDate>Wed, 25 Apr 2012 06:55:07 +0000</pubDate>
		<dc:creator>Derek Dieter</dc:creator>
				<category><![CDATA[Concurrency]]></category>
		<category><![CDATA[Query Optimizer]]></category>
		<category><![CDATA[TSQL]]></category>

		<guid isPermaLink="false">http://sqlserverplanet.com/?p=2310</guid>
		<description><![CDATA[There is definitely a lack of awareness in the SQL world regarding the use of user defined functions and the potential performance hit they can have when using within your queries. Don&#8217;t get me wrong, I would love nothing more than to be able to centralize my commonly used code into functions for reuse. In [...]]]></description>
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		<title>Auto Update Statistics &amp; Auto Create Statistics</title>
		<link>http://sqlserverplanet.com/query-optimizer/auto-update-statistics-auto-create-statistics</link>
		<comments>http://sqlserverplanet.com/query-optimizer/auto-update-statistics-auto-create-statistics#comments</comments>
		<pubDate>Mon, 19 Sep 2011 21:18:29 +0000</pubDate>
		<dc:creator>Derek Dieter</dc:creator>
				<category><![CDATA[DBA]]></category>
		<category><![CDATA[Query Optimizer]]></category>
		<category><![CDATA[SQL Optimization]]></category>
		<category><![CDATA[statistics]]></category>

		<guid isPermaLink="false">http://sqlserverplanet.com/?p=2208</guid>
		<description><![CDATA[The ability to create and update statistics is a crucial liberty for the query optimizer. The optimizer needs to know how it is going to query underlying tables, and when the statistics do not match the data, it is very probable that it will choose a non-efficient method for querying. I&#8217;ve seen and heard a [...]]]></description>
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		<title>Using DBCC UPDATEUSAGE</title>
		<link>http://sqlserverplanet.com/query-optimizer/using-dbcc-updateusage</link>
		<comments>http://sqlserverplanet.com/query-optimizer/using-dbcc-updateusage#comments</comments>
		<pubDate>Fri, 16 Sep 2011 23:18:36 +0000</pubDate>
		<dc:creator>Derek Dieter</dc:creator>
				<category><![CDATA[DBA]]></category>
		<category><![CDATA[Query Optimizer]]></category>

		<guid isPermaLink="false">http://sqlserverplanet.com/?p=2203</guid>
		<description><![CDATA[When DBCC UpdateUsage is run, page and row counts are updated. When this information is incorrect, it can give incorrect reports for how much space is used by tables and indexes. The most likely cause for incorrect usage stats is when a database is upgraded to a new compatibility level of SQL Server (i.e. 2000 [...]]]></description>
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		<title>SQL Server Join Algorithms</title>
		<link>http://sqlserverplanet.com/query-optimizer/sql-server-join-algorithms</link>
		<comments>http://sqlserverplanet.com/query-optimizer/sql-server-join-algorithms#comments</comments>
		<pubDate>Mon, 21 Feb 2011 04:52:00 +0000</pubDate>
		<dc:creator>Derek Dieter</dc:creator>
				<category><![CDATA[Query Optimizer]]></category>
		<category><![CDATA[SQL Optimization]]></category>

		<guid isPermaLink="false">http://sqlserverplanet.com/?p=1993</guid>
		<description><![CDATA[If you read execution plans enough, you&#8217;ve probably realized that when SQL Server joins tables together, it uses different internal algorithms. The three algorithms are: Loop Join Merge Join Hash Join These alogorithms that are used are based upon factors of the underlying data. Merge Join For the most part, this is the most efficient [...]]]></description>
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		<title>Using DBCC FREEPROCCACHE</title>
		<link>http://sqlserverplanet.com/query-optimizer/using-dbcc-freeproccache</link>
		<comments>http://sqlserverplanet.com/query-optimizer/using-dbcc-freeproccache#comments</comments>
		<pubDate>Wed, 08 Sep 2010 05:17:47 +0000</pubDate>
		<dc:creator>Derek Dieter</dc:creator>
				<category><![CDATA[DBA]]></category>
		<category><![CDATA[Query Optimizer]]></category>

		<guid isPermaLink="false">http://sqlserverplanet.com/?p=1669</guid>
		<description><![CDATA[The DBCC FREEPROCCACHE command clears the procedure cache for all the procedures on the server.  This command should be used with caution, however in most circumstances it will not bring a server to its knees. In order to execute in SQL 2005+, you need to have the server-level permissions of ALTER SERVER STATE. To use [...]]]></description>
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