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

Article translations Article translations
Article ID: 940545 - View products that this article applies to.
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.
Expand all | Collapse all

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.
  • Multiple INSERT operations from multiple connections occur against the table at the same time.
In this scenario, the performance of the INSERT operations may be much slower than the performance of similar operations in SQL Server 2000.

If you collect run-time information for the INSERT operations by running the DBCC SQLPERF('waitstats') statement for a specified interval, you notice that the following wait types are listed more frequently than they are listed in SQL Server 2000:
  • PAGELATCH_EX
  • PAGELATCH_SH
These wait types also require a longer wait time than they require in SQL Server 2000.

CAUSE

This problem occurs because of new page split logic in SQL Server 2005.

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 "Applies to" section.

MORE INFORMATION

By default, this hotfix is enabled after you apply it. To disable this hotfix, 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.

After you apply this hotfix, the contention on PAGELATCH_* wait types is reduced so that these wait types are comparable to what they were in SQL Server 2000. The hotfix does not eliminate these wait types.

When a clustered index references the identity column, concurrent INSERT operations try to access the first page or the last page of the table. By definition, these operations try to access the first page for descending identity values and try to access the last page for ascending identity values. This behavior occurs because the rows fall on the same page or on adjacent pages. Therefore, the choice of a clustered index naturally leads to more contention on the last page during concurrent INSERT operations. If this contention continues to occur after you apply the hotfix, consider changing the clustered index key so that the identity column is not the first index key column. A suitably selected clustered index key can spread the insertions so that they occur across many pages in the table instead of competing for the same page at the beginning or the end of the table.

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

REFERENCES

For more information about the list of builds that are available after SQL Server Service Pack 2, 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
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 problems
For more information about how to obtain SQL Server 2005 Service Pack 2, click the following article number to view the article in the Microsoft Knowledge Base:
913089 How to obtain the latest service pack for SQL Server 2005
For more information about the new features and the improvements in SQL Server 2005 Service Pack 2, visit the following Microsoft Web site:
http://go.microsoft.com/fwlink/?LinkId=71711
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:
822499 New naming schema for Microsoft SQL Server software update packages
For 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

Properties

Article ID: 940545 - Last Review: October 17, 2008 - Revision: 2.0
APPLIES TO
  • Microsoft SQL Server 2005 Standard Edition
  • Microsoft SQL Server 2005 Enterprise Edition
  • Microsoft SQL Server 2005 Developer Edition
  • Microsoft SQL Server 2005 Standard X64 Edition
  • Microsoft SQL Server 2005 Enterprise X64 Edition
  • Microsoft SQL Server 2005 Standard Edition for Itanium-based Systems
  • Microsoft SQL Server 2005 Enterprise Edition for Itanium-based Systems
Keywords: 
kbhotfixrollup kbfix kbpubtypekc kbqfe kbexpertiseadvanced KB940545

Give Feedback

 

Contact us for more help

Contact us for more help
Connect with Answer Desk for expert help.
Get more support from smallbusiness.support.microsoft.com