Article ID: 919638 - View products that this article applies to.
Consider the following scenario. You try to run a query in Microsoft SQL Server 2000. The query runs in a parallel plan. In this scenario, query performance may decrease.
Query performance may also decrease if the following conditions are true:
This problem may occur when SQL Server reorders a join in a derived table or in a view. If SQL Server reorders the join so that the join is performed after the UNION operation, the resulting query tree may have a project operator between the union and an anti-semijoin operator. This project operator implements the NOT IN operator or the NOT EXISTS clause.
In this scenario, SQL Server 2000 will not reorder the anti-semijoin around the intermediate project to allow for additional join reordering of the remaining tree. Therefore, query performance may decrease.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
Article ID: 919638 - Last Review: September 17, 2011 - Revision: 2.0