a9c7e709   
   From: esquel@sommarskog.se   
      
   Emin (emin.shopper@gmail.com) writes:   
   > I would like to explicitly prevent SQL Server 2005 from rewriting a   
   > query in my WHERE clause because the rewrite slows things down by many   
   > orders of magnitude.   
   >   
   > I have a query like   
   >   
   > SELECT * FROM A WHERE b in (31, 78)   
   >   
   > which takes forever (times out actually).   
   >   
   > If I instead do SELECT * FROM A WHERE b = 31 or if I do SELECT * FROM   
   > A WHERE b = 78, each query runs very quickly but the combination is   
   > incredibly slow despite the fact that I have indexes on appropriate   
   > things.   
   >   
   > After some investigation with the query optimizer, I determined that   
   > SQL Server is rewriting the predicate "b in (31, 78)" as (b>=31) AND   
   > (b<=78) as an intermediate step. I suspect this makes the query take a   
   > long time because there are *LOTS* of records with b>=31 and b<=78.   
      
   If that is happening, I would suspect that statistics are out   
   of date. What happens if you run UPDATE STATISTICS WITH FULLSCAN   
   on the table?   
      
   --   
   Erland Sommarskog, SQL Server MVP, esquel@sommarskog.se   
      
   Links for SQL Server Books Online:   
   SQL 2008: http://msdn.microsoft.com/en-us/sqlserver/cc514207.aspx   
   SQL 2005: http://msdn.microsoft.com/en-us/sqlserver/bb895970.aspx   
   SQL 2000: http://www.microsoft.com/sql/prodinfo/previousversions/books.mspx   
      
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