Microsoft KB Archive/940545

= FIX: The performance of insert operations against a table that contains an identity column may be slow in SQL Server 2005 =

Article ID: 940545

Article Last Modified on 8/10/2007

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APPLIES TO


 * Microsoft SQL Server 2005 Developer Edition
 * Microsoft SQL Server 2005 Enterprise Edition
 * Microsoft SQL Server 2005 Standard Edition
 * Microsoft SQL Server 2005 Standard X64 Edition
 * Microsoft SQL Server 2005 Standard Edition for Itanium-based Systems
 * Microsoft SQL Server 2005 Enterprise X64 Edition
 * Microsoft SQL Server 2005 Enterprise Edition for Itanium-based Systems

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Bug #: 50001602 (SQL Hotfix)



Microsoft distributes Microsoft SQL Server 2005 fixes as one downloadable file. Because the fixes are cumulative, each new release contains all the hotfixes and all the security fixes that were included with the previous SQL Server 2005 fix release.



SYMPTOMS
Consider the following scenario:
 * In Microsoft SQL Server 2005, a table contains an identity column.
 * You create a clustered index that references the identity column.
 * The identity column is the first column in the clustered index.
 * There are multiple insert operations against the table that occur at the same time from multiple connections.

In this scenario, the performance of the insert operations may be much slower than their performance in SQL Server 2000.

If you collect the runtime information for the insert operations in a period by running the DBCC SQLPERF('waitstats') statement for each specified interval, you notice that the following wait types are listed more frequently than they are listed in SQL Server 2000.
 * The PAGELATCH_EX wait type
 * The PAGELATCH_SH wait type

Additionally, these wait types require a longer wait time than they require in SQL Server 2000.



CAUSE
This issue occurs because of a new page split logic that is implemented in SQL Server 2005. The new page split logic causes SQL Server 2005 to take a longer wait time for the PAGELATCH_EX and PAGELATCH_SH wait types.



RESOLUTION
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 2005 Service Pack 2, click the following article number to view the article in the Microsoft Knowledge Base:

939537 Cumulative update package 3 for SQL Server 2005 Service Pack 2

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:

937137 The SQL Server 2005 builds that were released after SQL Server 2005 Service Pack 2 was released

Microsoft SQL Server 2005 hotfixes are created for specific SQL Server service packs. You must apply a SQL Server 2005 Service Pack 2 hotfix to an installation of SQL Server 2005 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 &quot;Applies to&quot; section.



MORE INFORMATION
By default, this hotfix is enabled after you apply this hotfix. If you want to disable this hotfix, you can use trace flag 698. This trace flag is a global trace flag. You can add this trace flag by using a parameter at the startup of the SQL Server service or by using the DBCC TRACEON statement.

For more information about what files are changed, and for information about any prerequisites to apply the cumulative update package that contains the hotfix that is described in this Microsoft Knowledge Base article, click the following article number to view the article in the Microsoft Knowledge Base:

939537 Cumulative update package 3 for SQL Server 2005 Service Pack 2

