FIX: An incorrect cardinality estimate is returned when you run a query in SQL Server 2005, SQL Server 2008, or SQL Server 2008 R2

When you run a query in Microsoft SQL Server 2005, Microsoft SQL Server 2008, or Microsoft SQL Server 2008 R2, an incorrect cardinality estimate is returned. For example, when you run the query, the actual number of rows is greater than 2000. However, the estimated number of rows is 1. This problem occurs when the following conditions are true:

• The query contains at least one JOIN clause.
• There are multiple columns in the WHERE clause.
• The SQL Server optimizer uses the Anti Semi Join operator to join data.

Cumulative update information

SQL Server 2005 Service Pack 3

The fix for this issue was first released in Cumulative Update 11 for SQL Server 2005 Service Pack 3. For more information about this cumulative update package, click the following article number to view the article in the Microsoft Knowledge Base:Note Because the builds are cumulative, each new fix release contains all the hotfixes and all the security fixes that were included with the previous SQL Server 2005 fix release. Microsoft recommends that you consider applying the most recent fix release that contains this hotfix. For more information, click the following article number to view the article in the Microsoft Knowledge Base: Microsoft SQL Server 2005 hotfixes are created for specific SQL Server service packs. You must apply a SQL Server 2005 Service Pack 3 hotfix to an installation of SQL Server 2005 Service Pack 3. By default, any hotfix that is provided in a SQL Server service pack is included in the next SQL Server service pack.

SQL Server 2008 Service Pack 1

The fix for this issue was first released in Cumulative Update 9 for SQL Server 2008 Service Pack 1. For more information about this cumulative update package, click the following article number to view the article in the Microsoft Knowledge Base:Note Because the builds are cumulative, each new fix release contains all the hotfixes and all the security fixes that were included with the previous SQL Server 2008 fix release. Microsoft recommends that you consider applying the most recent fix release that contains this hotfix. For more information, click the following article number to view the article in the Microsoft Knowledge Base: Microsoft SQL Server 2008 hotfixes are created for specific SQL Server service packs. You must apply a SQL Server 2008 Service Pack 1 hotfix to an installation of SQL Server 2008 Service Pack 1. By default, any hotfix that is provided in a SQL Server service pack is included in the next SQL Server service pack.

SQL Server 2008 Service Pack 2

The fix for this issue was first released in Cumulative Update 1 for SQL Server 2008 Service Pack 2. For more information about this cumulative update package, click the following article number to view the article in the Microsoft Knowledge Base: Note Because the builds are cumulative, each new fix release contains all the hotfixes and all the security fixes that were included with the previous SQL Server 2008 fix release. We recommend that you consider applying the most recent fix release that contains this hotfix. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

SQL Server 2008 R2

The fix for this issue was first released in Cumulative Update 4. For more information about how to obtain this cumulative update package for SQL Server 2008 R2, click the following article number to view the article in the Microsoft Knowledge Base:Note Because the builds are cumulative, each new fix release contains all the hotfixes and all the security fixes that were included with the previous SQL Server 2008 R2 fix release. We recommend that you consider applying the most recent fix release that contains this hotfix. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

You can view the estimated rows for the query by looking at the EstimateRows column of the SHOWPLAN_ALL output or of the STATISTICS PROFILE output.

For more information about the Anti Semi Join operator, visit the following Microsoft Developer Network (MSDN) websites: For more information about the Incremental Servicing Model for SQL Server, click the following article number to view the article in the Microsoft Knowledge Base: For more information about the naming schema for SQL Server updates, click the following article number to view the article in the Microsoft Knowledge Base:
For more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base: