BUG: IN Subquery Reformats and Is Slower Than an Equivalent Join
Article ID: 173314
Article Last Modified on 10/16/2003
APPLIES TO
- Microsoft SQL Server 6.5 Standard Edition
- Microsoft SQL Server 6.0 Standard Edition
This article was previously published under Q173314
SYMPTOMS
BUG #: 17227 (6.5)
A join combined with an IN subquery may cause a reformat access plan and be
much slower than the logically equivalent pure join query. In general, an
IN subquery should have approximately the same performance as the
equivalent join.
WORKAROUND
Express the IN subquery as join, or break it down to several smaller
queries using temporary tables, which collectively produce the same result.
STATUS
Microsoft has confirmed this to be a problem in Microsoft SQL Server
versions 6.0 and 6.5. We are researching this problem and will post new
information here in the Microsoft Knowledge Base as it becomes available.
Additional query words: sub
Keywords: kbbug kbusage KB173314