FIX: Updates That Run at a Read Uncommitted Isolation Level Fail with a 644 Error Message

An update statement may fail, and you receive this 644 error message when both of the following conditions are met:

• A query is running under the Read Uncommitted isolation level.
  
  -and-
• The query plan contains a sort or spool operator between the update operator and the seek or scan operator on the base table.

To resolve this problem, obtain the latest service pack For Microsoft SQL Server 2000. For additional information, click the following article number To view the article In the Microsoft Knowledge Base: NOTE: The following hotfix was created before the release of Microsoft SQL Server 2000 Service Pack 3.

The English version of this fix has the file attributes (or later) that are listed in the following table. The dates and times for these files are listed in coordinated universal time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel. NOTE: Because of file dependencies, the most recent hotfix or feature that contains the files may also contain additional files.

To work around this behavior, use the default isolation level (Read Committed) during updates.

Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article.
This problem was first corrected In Microsoft SQL Server 2000 Service Pack 3.

Here is a list of the methods that you can use to view a query plan:

• From Query Analyzer, run the following command:

  SET SHOWPLAN_ALL ON
  GO
  -- Now run the Update query in question
  SET SHOWPLAN_ALL OFF
  GO

• From Query Analyzer, run the following command:

  SET STATISTICS PROFILE ON
  GO
  -- Now run the Update query in question
  SET STATISTICS PROFILE OFF
  GO

• Add the following event to a default profiler trace definition file:

  Performance -> Show Plan Statistics