Microsoft KB Archive/841627

= FIX: SQL Server 2000 may underestimate the cardinality of a query expression under certain circumstances =

Article ID: 841627

Article Last Modified on 11/2/2007

-

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

-



Bug #: 471399 (SQL Server 8.0)



Microsoft SQL Server 2000 fixes are distributed as one downloadable file. Because the fixes are cumulative, each new release contains all the hotfixes and all the security fixes that were included with the previous SQL Server 2000 fix release.



SYMPTOMS
When you run a Transact-SQL query, Microsoft SQL Server 2000 may underestimate the cardinality of the query expression. Therefore, the SQL Server query optimizer may not be able to generate an optimal query execution plan, and the query performance may be slow and inconsistent. This problem occurs when both of the following conditions are true:
 * The max degree of parallelism configuration option for your instance of SQL Server is set to 0 or to a number that is greater than 1.
 * The query is based on a view.



Service pack information
To resolve this problem, obtain the latest service pack for Microsoft SQL Server 2000. For more 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 hotfix 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 ---  27-Apr-2004  05:33  2000.80.936.0     664,128  Autoplt.dll 27-Apr-2004 05:33  2000.80.936.0      78,400  Console.exe 27-Apr-2004 05:33  2000.80.936.0     315,968  Custtask.dll 27-Apr-2004 05:33  2000.80.936.0      33,340  Dbmslpcn.dll 08-Apr-2004 09:12                    786,432  Distmdl.ldf 08-Apr-2004 09:12                  2,359,296  Distmdl.mdf 10-Oct-2003 06:18                        180  Drop_repl_hotfix.sql 27-Apr-2004 05:33  2000.80.936.0   1,905,216  Dtspkg.dll 27-Apr-2004 05:33  2000.80.936.0     528,960  Dtspump.dll 27-Apr-2004 05:33  2000.80.936.0   1,557,052  Dtsui.dll 27-Apr-2004 05:33  2000.80.936.0     639,552  Dtswiz.dll 10-Oct-2003 06:18                    747,927  Instdist.sql 10-Oct-2003 06:18                      1,581  Inst_repl_hotfix.sql 27-Apr-2004 05:33  2000.80.936.0      82,492  Itwiz.exe 27-Apr-2004 05:33  2000.80.936.0      90,692  Msgprox.dll 27-Apr-2004 05:33  2000.80.936.0      62,024  Odsole70.dll 27-Apr-2004 05:34  2000.80.936.0      25,144  Opends60.dll 27-Apr-2004 05:33  2000.80.936.0      57,904  Osql.exe 27-Apr-2004 05:33  2000.80.936.0     279,104  Pfutil80.dll 10-Oct-2003 06:07                    550,780  Procsyst.sql 08-Apr-2004 09:12                     12,305  Qfe469315.sql 08-Apr-2004 09:12                     19,195  Qfe469571.sql 27-Apr-2004 04:24                  1,104,848  Replmerg.sql 27-Apr-2004 05:33  2000.80.936.0     221,768  Replprov.dll 27-Apr-2004 05:33  2000.80.936.0     307,784  Replrec.dll 27-Apr-2004 04:32  2000.80.936.0     159,813  Replres.rll 10-Oct-2003 06:18                  1,087,150  Replsys.sql 10-Oct-2003 06:18                    986,603  Repltran.sql 27-Apr-2004 05:33  2000.80.936.0     287,304  Rinitcom.dll 27-Apr-2004 05:33  2000.80.936.0      66,112  Semmap.dll 27-Apr-2004 05:33  2000.80.936.0      57,916  Semnt.dll 27-Apr-2004 05:33  2000.80.936.0     492,096  Semobj.dll 27-Apr-2004 05:00  2000.80.936.0     172,032  Semobj.rll 27-Apr-2004 05:33  2000.80.936.0      53,832  Snapshot.exe 11-Mar-2004 14:40                    117,834  Sp3_serv_uni.sql 27-Apr-2004 05:32  2000.80.936.0      28,672  Sqlagent.dll 27-Apr-2004 05:33  2000.80.936.0     311,872  Sqlagent.exe 27-Apr-2004 05:32  2000.80.936.0     168,001  Sqlakw32.dll 27-Apr-2004 05:33  2000.80.936.0      33,344  Sqlctr80.dll 27-Apr-2004 05:33  2000.80.936.0   4,215,360  Sqldmo.dll 27-Apr-2004 05:33                     25,172  Sqldumper.exe 27-Apr-2004 04:22  2000.80.936.0      28,672  Sqlevn70.rll 27-Apr-2004 05:33  2000.80.936.0     180,792  Sqlmap70.dll 27-Apr-2004 05:33  2000.80.936.0     188,992  Sqlmmc.dll 27-Apr-2004 05:01  2000.80.936.0     479,232  Sqlmmc.rll 27-Apr-2004 05:33  2000.80.936.0     401,984  Sqlqry.dll 27-Apr-2004 05:33  2000.80.936.0      57,920  Sqlrepss.dll 27-Apr-2004 05:34  2000.80.936.0   7,581,777  Sqlservr.exe 27-Apr-2004 05:33  2000.80.936.0     590,396  Sqlsort.dll 27-Apr-2004 05:33  2000.80.936.0      45,644  Sqlvdi.dll 27-Apr-2004 05:33  2000.80.936.0     106,588  Sqsrvres.dll 27-Apr-2004 05:33  2000.80.936.0      33,340  Ssmslpcn.dll 27-Apr-2004 05:33  2000.80.936.0      82,492  Ssnetlib.dll 27-Apr-2004 05:33  2000.80.936.0      25,148  Ssnmpn70.dll 27-Apr-2004 05:33  2000.80.936.0     123,456  Stardds.dll 27-Apr-2004 05:33  2000.80.936.0     158,240  Svrnetcn.dll 27-Apr-2004 05:33  2000.80.936.0      76,416  Svrnetcn.exe 27-Apr-2004 05:34  2000.80.936.0      49,228  Ums.dll 27-Apr-2004 05:34  2000.80.936.0      98,872  Xpweb70.dll Note Because of file dependencies, the most recent hotfix or feature that contains these files may also contain additional files.



WORKAROUND
To work around this problem, you must rewrite the query so that the query is based directly on the tables, instead of on the view. You can also rewrite the query to include the OPTION (MAXDOP =1) query hint to override the max degree of parallelism configuration option.



STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the &quot;Applies to&quot; section.

This problem was first corrected in Microsoft SQL Server 2000 Service Pack 4.

