BUG: Extraneous Locks During UPDATE on Table w/ > 15 Indexes

• Microsoft SQL Server, version 6.0

SYMPTOMS

Running an UPDATE on a table results in more EX_PAGE locks when the table contains more than 15 indexes, even when the column being updated is not a part of any index. The same set of statements uses a smaller number of locks if there are 15 or fewer indexes on the updated table.

STATUS

Microsoft has confirmed this to be a problem in Microsoft SQL Server version 6.0. We are researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.

This problem does not occur in Microsoft SQL Server version 6.5.

MORE INFORMATION

When the table contains more than 15 indexes, the index pages were locked by an update statement even though the update did not affect any of the indexes. This causes additional locks on index pages that contain columns not involved in the query/update statement. This results in reduced concurrency with 16 or more indexes on the table being updated.