BUG: Non-Indexed Joins May Skip Optimizer's Reformatting Step

• Microsoft SQL Server, version 6.5

       17158 (6.5)

SYMPTOMS

You may experience impaired performance when you process queries involving joins on tables with no defined indexes. This problem has been identified on SQL Server 6.5 only with Service Pack 2 and Service Pack 3 (and intermediate builds between them). In one scenario, a query involving a non- indexed join took approximately 840 minutes to execute on SQL Server 6.5 Service Pack 2, but only one minute on the release version of SQL Server 6.5. You may experience the degraded performance whether you use an ad-hoc query or execute it within a stored procedure.

CAUSE

The Optimizer skips the Reformatting step for large tables with no indexes defined. Earlier versions of SQL Server benefit significantly with the Reformatting step included.

WORKAROUND

To work around this problem, define indexes on the tables.

STATUS

Microsoft has confirmed this to be a problem in Microsoft SQL Server version 6.5. We are researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.

MORE INFORMATION

For more information, see the following article in the Microsoft Knowledge Base:

   ARTICLE-ID: Q110352
   TITLE     : INF: Optimizing Microsoft SQL Server Performance