Microsoft KB Archive/224539

= FIX: Query Optimizer Fails to Consider Anti Semi Join for NOT IN Queries =

Article ID: 224539

Article Last Modified on 3/14/2006

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APPLIES TO


 * Microsoft SQL Server 7.0 Standard Edition

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This article was previously published under Q224539



BUG #: 53568 (SQLBUG_70)



SYMPTOMS
For queries that contain a predicate ... IN (a, b, c, ...), the SQL Server 7.0 optimizer evaluates the possibility of converting the query to a semi join. However, it fails to consider a similar simplification that would simplify a ... NOT IN (a, b, c, ...) as an anti semi join. Thus, a NOT IN query returning a similar number of rows may take considerably longer to run than a corresponding query using IN.



WORKAROUND
To work around this problem, explicitly create and populate an intermediate table with this list of values from the NOT IN clause, and rewrite the query using a join.



STATUS
Microsoft has confirmed this to be a problem in SQL Server 7.0. This problem has been corrected in U.S. Service Pack 1 for Microsoft SQL Server 7.0. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

232570INF: How to Obtain Service Pack 1 for Microsoft SQL Server 7.0 and Microsoft Data Engine (MSDE) 1.0

For more information, contact your primary support provider.

Additional query words: optimizer showplan performance slow

Keywords: kbbug kbfix kbqfe KB224539

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