In Microsoft SQL Server 2005, Microsoft SQL Server 2008, or Microsoft SQL Server 2008 R2, when you run the ALTER TABLE statement to alter an XML data type column in a table from NOT NULL to NULL, the following issues may occur:

• SQL Server 2005, SQL Server 2008, or SQL Server 2008 R2 requires a long time to finish the processing.
• SQL Server 2005, SQL Server 2008, or SQL Server 2008 R2 generates a large amount of transaction log data.
  

For example, you have 1 million rows in the table. In this case, SQL Server 2005, SQL Server 2008, or SQL Server 2008 R2 may use more than one minute to alter the XML column. Additionally, the size of transaction log data grows from a small value such as 8192 KB to a large value such as 1,008,000 KB.

Cumulative update information

SQL Server 2005

The fix for this issue was first released in Cumulative Update 10 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 3. 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 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 how to obtain SQL Server 2005 Service Pack 3, click the following article number to view the article in the Microsoft Knowledge Base: For more information about new features and improvements in SQL Server 2005 Service Pack 3, visit the following Microsoft Web site: 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: