Consider the following scenario:

• You upgrade Microsoft SQL Server 2000 to Microsoft SQL Server 2008 or SQL Server 2008 R2.
• You run a query that uses a user-defined scalar function.

In this scenario, the query may require more time to complete compared to the time that is required before the upgrade.

Note This issue usually occurs when a nondeterministic function accesses data in the database.

This issue occurs because a suboptimal query plan is created for the query. Therefore, the user-defined scalar function is called more times than necessary.

Cumulative update information

SQL Server 2008 Service Pack 1

The fix for this issue was first released in Cumulative Update 10 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.

After you apply the cumulative update, you must enable trace flag 4199 to enable the fix. You can enable the trace flag by running the "DBCC TRACEON(4199, -1)" command for an individual session, or by adding the "-T4199" startup parameter.

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 5. 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.

For more information about how to design user-defined functions, visit the following Microsoft Developer Network (MSDN) website: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: