Microsoft KB Archive/822746

= FIX: Incorrect Results From a Parallel Query That Uses a UNION and Variables or Parameters =

Article ID: 822746

Article Last Modified on 11/2/2007

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APPLIES TO


 * Microsoft SQL Server 2000 Developer Edition
 * Microsoft SQL Server 2000 Standard Edition
 * Microsoft SQL Server 2000 Enterprise Edition
 * Microsoft SQL Server 2000 Personal Edition
 * Microsoft SQL Server 2000 Enterprise Edition
 * Microsoft SQL Server 2000 Workgroup Edition
 * Microsoft SQL Server 2000 Desktop Engine (Windows)
 * Microsoft SQL Server 2000 Developer Edition
 * Microsoft SQL Server 2000 Enterprise Edition 64-bit

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SYMPTOMS
You may receive incorrect results, if your query meets the following conditions:
 * The query specifies a UNION or a UNION ALL of two or more inputs.
 * In the UNION, at least one of the SELECT statements return the parameter or variable value (that is, it uses this value in the select list and not in the where clause).
 * The column returning the variable or parameter value is being used as a join or grouping column higher in the query tree, and this operator is run in parallel, requiring that the data stream be partitioned based on the join or grouping columns.

The following query is an example of one that is subject to this problem:

DECLARE @a SMALLINT SET @a=1

SELECT yy, COUNT(*) FROM (    SELECT productid xx, @a yy FROM products    UNION ALL    SELECT productid xx, unitsinstock yy FROM products     ) zz GROUP BY yy Note This query is not a reproduce scenario for the Northwind database. It is only there to show the form and syntax of a hypothetical query on a hypothetical table named products.



Service pack information
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 How to obtain the latest SQL Server 2000 service pack

Hotfix information
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.   Date         Time   Version         Size             File name ---  31-May-2003  18:45  2000.80.818.0      78,400 bytes  Console.exe 25-Jun-2003 01:01  2000.80.818.0      33,340 bytes  Dbmslpcn.dll 25-Apr-2003 02:12                    786,432 bytes  Distmdl.ldf 25-Apr-2003 02:12                  2,359,296 bytes  Distmdl.mdf 30-Jan-2003 01:55                        180 bytes  Drop_repl_hotfix.sql 23-Jun-2003 22:40  2000.80.837.0   1,557,052 bytes  Dtsui.dll 23-Jun-2003 22:40  2000.80.837.0     639,552 bytes  Dtswiz.dll 24-Apr-2003 02:51                    747,927 bytes  Instdist.sql 03-May-2003 01:56                      1,581 bytes  Inst_repl_hotfix.sql 08-Feb-2003 06:40  2000.80.765.0      90,692 bytes  Msgprox.dll 01-Apr-2003 02:07                      1,873 bytes  Odsole.sql 05-Apr-2003 01:46  2000.80.800.0      62,024 bytes  Odsole70.dll 07-May-2003 20:41  2000.80.819.0      25,144 bytes  Opends60.dll 02-Apr-2003 21:48  2000.80.796.0      57,904 bytes  Osql.exe 02-Apr-2003 23:15  2000.80.797.0     279,104 bytes  Pfutil80.dll 22-May-2003 22:57                     19,195 bytes  Qfe469571.sql 12-Jun-2003 16:37                  1,083,989 bytes  Replmerg.sql 04-Apr-2003 21:53  2000.80.798.0     221,768 bytes  Replprov.dll 08-Feb-2003 06:40  2000.80.765.0     307,784 bytes  Replrec.dll 05-May-2003 00:05                  1,085,874 bytes  Replsys.sql 01-Jun-2003 01:01  2000.80.818.0     492,096 bytes  Semobj.dll 31-May-2003 18:27  2000.80.818.0     172,032 bytes  Semobj.rll 29-May-2003 00:29                    115,944 bytes  Sp3_serv_uni.sql 01-Jun-2003 01:01  2000.80.818.0   4,215,360 bytes  Sqldmo.dll 07-Apr-2003 17:44                     25,172 bytes  Sqldumper.exe 19-Mar-2003 18:20  2000.80.789.0      28,672 bytes  Sqlevn70.rll 02-Jul-2003 00:18  2000.80.834.0     180,736 bytes  Sqlmap70.dll 08-Feb-2003 06:40  2000.80.765.0      57,920 bytes  Sqlrepss.dll 23-Jun-2003 22:40  2000.80.837.0   7,553,105 bytes  Sqlservr.exe 08-Feb-2003 06:40  2000.80.765.0      45,644 bytes  Sqlvdi.dll 25-Jun-2003 01:01  2000.80.818.0      33,340 bytes  Ssmslpcn.dll 01-Jun-2003 01:01  2000.80.818.0      82,492 bytes  Ssnetlib.dll 01-Jun-2003 01:01  2000.80.818.0      25,148 bytes  Ssnmpn70.dll 01-Jun-2003 01:01  2000.80.818.0     158,240 bytes  Svrnetcn.dll 31-May-2003 18:59  2000.80.818.0      76,416 bytes  Svrnetcn.exe 30-Apr-2003 23:52  2000.80.816.0      45,132 bytes  Ums.dll 02-Jul-2003 00:19  2000.80.834.0      98,816 bytes  Xpweb70.dll Note Because of file dependencies, the most recent hotfix or feature that contains the files may also contain additional files.



WORKAROUND
One of the requirements to result in this incorrect results scenario is that the query picks a parallel plan. To work around this problem, you can disable parallelism either at the query level by using a &quot;MAXDOP 1&quot; hint (see SQL Server Books Online for more information), or at a server level by setting the configuration parameter &quot;Max Degree of Parallelism&quot; to 1 (by using the sp_configure stored procedure).



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 4.

Keywords: kbbug kbfix kbqfe kbsqlserv2000presp4fix kbhotfixserver KB822746

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