FIX: High memory consumption may occur when you rebuild a single partition of the heap table in SQL Server 2008 or SQL Server 2008 R2

Consider the following scenario:

• You have a heap table and a nonclustered index that is in the heap table. The heap table contains many rows.
  For example, the heap table has more than 10 million rows.
• The heap table and the nonclustered index partitioned by using the same partition function.
• You try to rebuild a single partition of the heap table.
  

In this scenario, SQL Server incorrectly consumes a large amount of memory.

Note This issue may occur even if the partition is empty.

This issue occurs because a sort operation of the rebuild operation reserves memory incorrectly.

When SQL Server rebuilds a single partition, SQL Server rebuilds the nonclustered index, and SQL Server sorts the rows from the new location of the partition. However, the memory for this sort operation is reserved incorrectly based on the size of the whole heap table. Therefore, a large amount of memory is consumed.

Note A more efficient sort operation is based on the size of the single partition.

Cumulative update information

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:

SQL Server 2008 SP1

The fix for this issue was first released in Cumulative Update 11. For more information about how to obtain this cumulative update package for SQL Server 2008 Service Pack 1 (SP1), 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 Service Pack 1 (SP1) 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 Service Pack 2

The fix for this issue was first released in Cumulative Update 2 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. 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 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.

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 use the ALTER TABLE Transact-SQL statement, visit the following Microsoft Developer Network (MSDN) website: