FIX: Query Slow w/ ORDER BY DESC on Table w/ Composite Index

• Microsoft SQL Server version 6.5

SYMPTOMS

An ORDER BY DESC query against a table that has a non-clustered composite index may take significantly longer to run than the equivalent ASC query. This difference is especially noticed in cases in which a WHERE clause contains an equivalency test of an indexed column (including the most significant) and a constant value.

WORKAROUND

To work around this problem, select the result set (ASC) into a temporary table, then run the ORDER BY DESC query only on the results of a select from the temporary table.

Another option, for certain numeric columns, is to multiply the key by -1 and then run the ORDER BY ASC query.

STATUS

Microsoft has confirmed this to be a problem in Microsoft SQL Server version 6.5. This problem has been corrected in U.S. Service Pack 3 for Microsoft SQL Server version 6.5. For more information, contact your primary support provider.

Additional query words: descending

Keywords          : kbprg kbusage SSrvGen SSrvProg kbbug6.50 
Version           : 6.5
Platform          : WINDOWS 
Issue type        : kbbug 

Last Reviewed: April 9, 1999