Article ID: 322871 - Last Review: September 27, 2005 - Revision: 4.2

FIX: Incorrect Results May Occur with Index Spool and Parallel Plan

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This article was previously published under Q322871

BUG #: 357397 (SHILOH_BUGS)

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SYMPTOMS

A parallel query plan that contains an Index Spool operator, with an OUTER REFERENCES for a column under the spool, may produce incorrect results. An example of such a query plan is:

|--Nested Loops(Left Semi Join, [...] OUTER REFERENCES:([IssuesAre].[TreeID]))
    |--Index Spool(SEEK:([TreeNodesShadow].[L] >= [TreeNodes].[L] AND [TreeNodesShadow].[L] <= [TreeNodes].[R]))         
    |   |--Clustered Index Seek(OBJECT:([reprobug].[dbo].[TreeNodesShadow].[PK__TreeNodesShadow__571DF1D5]), SEEK:([TreeNodesShadow].[ID]=[IssuesAre].[TreeID]), ...
    |--Index Seek ...

Note that the IssuesAre.TreeID shown in the OUTER REFERENCES is a column that is used in the clustered index SEEK inside the index spool operator.

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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:

290211 (http://support.microsoft.com/kb/290211/EN-US/ ) INF: How To Obtain the Latest SQL Server 2000 Service Pack

NOTE: The following hotfix was created before the release of Microsoft SQL Server 2000 Service Pack 3.

The English version of this fix should have the following file attributes or later:

   Version       File name
   --------------------------

   8.00.0629     Sqlservr.exe

NOTE: Because of file dependencies, the most recent hotfix or feature that contains the files may also contain additional files.

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WORKAROUND

Because the problem only occurs with a parallel plan, you can temporarily avoid the problem by forcing a serial plan by using the query hint OPTION (MAXDOP 1), or by changing the max degree of parallelism configuration option.

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STATUS

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.

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