KB153921 - PRB: Extraneous Extent Locks Obtained During Data Modification

Article ID: 153921

Article Last Modified on 3/16/2005

APPLIES TO

Microsoft SQL Server 6.0 Standard Edition
Microsoft SQL Server 6.5 Standard Edition

This article was previously published under Q153921

SYMPTOMS

Extra Extent locks, located on the next and previous Extents, are being held during data modification statements.

WORKAROUND

There are two possible workarounds to this problem:

Increase the configuration option "Locks" to a sufficiently high value.
Break down the data modification statements into smaller transactions affecting fewer rows.

MORE INFORMATION

Extent locks are internal locks used by the server for locking Extents. User queries cannot reference or control Extent locking.

For more information, please see the following article in the Microsoft Knowledge Base:

61795 : INF: SQL Server Extent Allocation Information.

With data modification statements such as insert, update, and delete, Extent locks are obtained by the server for the purpose of storage structure management. When the transaction results in changes to the Extent structures, locks are also needed on the previous and next Extents to maintain the integrity of the Extent chain. The extra locks were the locks on the next and previous Extents.

This behavior is exhibited noticeably by replication-related tasks, specifically the cleanup task, since cleanup deletes records from distribution database tables and hence can run out of locks on large systems.

Additional query words: extent lock error 1204

Keywords: kbbug kbfix kbprb KB153921