Microsoft distributes Microsoft SQL Server 2008 R2 or Microsoft SQL Server 2008 or Microsoft SQL Server 2012 fixes in one downloadable file. Because the fixes are cumulative, each new release contains all the hotfixes and all the security updates that were included with the previous SQL Server 2008 R2 or SQL Server 2008 or Microsoft SQL Server 2012 update release.
Symptoms
Consider the following scenario. You run a query that contains several AND predicates in Microsoft SQL Server 2008, in Microsoft SQL Server 2008 R2, or in Microsoft SQL Server 2012. The conditions of the AND predicates are correlated. In this scenario, you experience poor performance in SQL Server 2008. For example, this issue occurs when you run a query that resembles the following:
(column1 = constant1 or column1 = constant2 or …) and (column2 = constant3 or column2 = constant4 or …) and …
Cause
This issue occurs because the query optimizer selects an inefficient query plan if the query contains correlated AND predicates. When the estimated number of rows meets the conditions of an AND predicate, SQL Server assumes that all conditions are independent. If the conditions are correlated, SQL Server underestimates the cardinality for the AND predicates.
Resolution
To resolve this issue, apply the following cumulative update. After you apply the update, you must enable trace flag 4137 to add the new logic for the cardinality estimation of AND predicates.Note This update applies only to filter predicates.
Cumulative update information
SQL Server 2008 Service Pack 3
The fix for this issue was first released in Cumulative Update 7 for SQL Server 2008 Service Pack 3. For more information about how to obtain this cumulative update package, click the following article number to view the article in the Microsoft Knowledge Base:
2738350 Cumulative Update package 7 for SQL Server 2008 Service Pack 3Note 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 Service Pack 3 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:
2629969 The SQL Server 2008 builds that were released after SQL Server 2008 Service Pack 3 was released
SQL Server 2012
The fix for this issue was first released in Cumulative Update 1 for SQL Server 2012. For more information about this cumulative update package, click the following article number to view the article in the Microsoft Knowledge Base:
2679368 Cumulative update package 1 for SQL Server 2012Note 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 2012 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:
2692828 The SQL Server 2012 builds that were released after SQL Server 2012 was released You must apply a SQL Server 2012 hotfix to an installation of SQL Server 2012.
SQL Server 2008 R2 Service Pack 1
The fix for this issue was first released in Cumulative Update 5 for SQL Server 2008 R2 Service Pack 1. For more information about how to obtain this cumulative update package, click the following article number to view the article in the Microsoft Knowledge Base:
2659694 Cumulative Update package 5 for SQL Server 2008 R2 Service Pack 1Note 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:
2567616 The SQL Server 2008 R2 builds that were released after SQL Server 2008 R2 Service Pack 1 was released
SQL Server 2008 Service Pack 2
The fix for this issue was first released in Cumulative Update 8 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:
2648096 Cumulative update package 8 for SQL Server 2008 Service Pack 2Note 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:
2402659 The SQL Server 2008 builds that were released after SQL Server 2008 Service Pack 2 was released Microsoft SQL Server 2008 hotfixes are created for specific SQL Server service packs. You must apply a SQL Server 2008 Service Pack 2 hotfix to an installation of SQL Server 2008 Service Pack 2. By default, any hotfix that is provided in a SQL Server service pack is included in the next SQL Server service pack.
Status
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
References
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:
935897 An Incremental Servicing Model is available from the SQL Server team to deliver hotfixes for reported problemsFor more information about the naming schema for SQL Server updates, click the following article number to view the article in the Microsoft Knowledge Base:
822499Naming schema for Microsoft SQL Server software update packagesFor more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base:
824684 Description of the standard terminology that is used to describe Microsoft software updates
