A software update is available to optimize the presence update logic in Live Communications Server 2005 (913002)

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In a front-end and back-end Live Communications Server 2005 implementation, the back-end Live Communications Server computer updates users' presence information in the Microsoft SQL Server database. Live Communications Server 2005 assigns a sequence number to each of these presence updates. Because of how SQL Server handles this query, SQL Server locks the tables during the query execution. You may have many locks created at the same time if all the following conditions are true:

• You have a large Live Communications Server deployment.
• Many users have lots of contacts to whom they provide updated presence information.
• These many users frequently change their presence status.

In this scenario, the presence information change for one user may generate presence information updates for hundreds of other users. Sometimes, the combination of these conditions could lead to a deadlock scenario. In this scenario, presence information is not updated correctly when a user's presence status changes. For example, a user might have a presence of Away even if that user is currently using the computer.

This software update enhances how Live Communications Server 2005 processes presence information. After you install this software update, Live Communications Server still assigns a sequence number when it updates presence information. However, the back-end Live Communications Server computer no longer performs the presence update functionality. After you install this software update, the front-end Live Communications Server computer updates presence information. Because the presence update logic is moved to the front-end Live Communications Server computer, Live Communications Server 2005 better controls how SQL Server handles the resulting database queries. This presence update design change removes the requirement for SQL Server to lock the database tables during the database query. Because SQL Server no longer locks the database tables during these queries, no deadlock issue can occur. Therefore, even with a high contact-to-user ratio, Live Communications Server 2005 can update presence information more efficiently.

To resolve this issue, install the software update that is described in the following Microsoft Knowledge Base article: For more information about the terminology that Microsoft uses for software that is corrected after it is released, click the following article number to view the article in the Microsoft Knowledge Base: