Microsoft KB Archive/892392

= FIX: Query performance may be slower if the query contains both a GROUP BY clause and a DISTINCT keyword on the same column =

Article ID: 892392

Article Last Modified on 11/2/2007

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APPLIES TO


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

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Bug #: 473244 (SQL Server 8.0)



''Microsoft distributes Microsoft SQL Server 2000 fixes 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.''



SUMMARY
This article describes the following about this hotfix release:
 * The issues that are fixed by this hotfix package
 * The prerequisites for installing the hotfix package
 * Whether you must restart the computer after you install the hotfix package
 * Whether the hotfix package is replaced by any other hotfix package
 * Whether you must make any registry changes
 * The files that are contained in the hotfix package

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SYMPTOMS
After you upgrade to Microsoft SQL Server 2000 from SQL Server 7.0, query performance may be slower if the query contains both a GROUP BY clause and a DISTINCT keyword on the same column. For example, a query that is similar to the following may perform slower after you upgrade to SQL Server 2000: SELECT MAX(B.OrderDate), A.ExpensePeriod, B.TransactionType FROM (SELECT DISTINCT ExpensePeriod FROM ExpensesPaid) A, Orders GROUP BY A.ExpensePeriod, B.TransactionType HAVING (B.TransactionType = 'R') Note In this query, the A.ExpensePeriod column is used in both the DISTINCT keyword and in a GROUP BY clause.

For a list of all publicly released SQL Server 2000 post-Service Pack 3a hotfixes, see the following article in the Microsoft Knowledge Base:

810185 SQL Server 2000 hotfix update for SQL Server 2000 Service Pack 3 and 3a

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CAUSE
In SQL Server 2000, the query optimizer removes unnecessary operations. When a query contains a GROUP BY clause and a DISTINCT keyword on the same column, the query is simplified, and the duplication is removed. Therefore, when you run the query in SQL Server 7.0, a Stream Aggregation may be used first to aggregate the data. In SQL Server 2000, a Hash Aggregation may be used first. In rare situations, the new execution plan may cause slower performance.

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Hotfix information
A supported hotfix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Only apply it to systems that are experiencing this specific problem. This hotfix may receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next Microsoft SQL Server 2000 service pack that contains this hotfix.

To resolve this problem immediately, contact Microsoft Product Support Services to obtain the hotfix. For a complete list of Microsoft Product Support Services telephone numbers and information about support costs, visit the following Microsoft Web site:

http://support.microsoft.com/contactus/?ws=support

Note In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

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Prerequisites
To install this hotfix, you must have the following prerequisites:  SQL Server 2000 Service Pack 3 (SP3)

For information about how to obtain SQL Server 2000 SP3, see the following article in the Microsoft Knowledge Base:

290211 How to obtain the latest SQL Server 2000 service pack

 SQL Server 2000 hotfix build 2000.80.0977

For more information about SQL Server 2000 post-SP3a hotfix build 2000.80.0977, click the following article number to view the article in the Microsoft Knowledge Base:

888007 You receive a &quot;The product does not have a prerequisite update installed&quot; error message when you try to install a SQL Server 2000 post-Service Pack 3 hotfix



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Restart information
You do not have to restart the computer after you apply this hotfix.

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Registry information
You do not have to change the registry.

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Hotfix file information
This hotfix contains only those files that are required to correct the issues that this article lists. This hotfix may not contain of all the files that you must have to fully update a product to the latest build.

The English version of this hotfix has the file attributes (or later file attributes) 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.

SQL Server 2000 32-bit versions
  Date         Time   Version            Size    File name --  07-Jan-2005  02:11  2000.80.1000.0    664,128  Autoplt.dll 07-Jan-2005 02:10  2000.80.1000.0     78,400  Console.exe 07-Jan-2005 02:11  2000.80.1000.0    332,352  Ctasksui.dll 07-Jan-2005 02:11  2000.80.1000.0    315,968  Custtask.dll 07-Jan-2005 02:11  2000.80.1000.0     33,340  Dbmslpcn.dll 31-Dec-2004 17:31                    786,432  Distmdl.ldf 31-Dec-2004 17:31                  2,359,296  Distmdl.mdf 31-Dec-2004 17:31                        180  Drop_repl_hotfix.sql 07-Jan-2005 02:11  2000.80.1000.0  1,905,216  Dtspkg.dll 07-Jan-2005 02:11  2000.80.1000.0    528,960  Dtspump.dll 07-Jan-2005 02:11  2000.80.1000.0  1,557,052  Dtsui.dll 07-Jan-2005 02:11  2000.80.1000.0    639,552  Dtswiz.dll 31-Dec-2004 17:31                    747,927  Instdist.sql 31-Dec-2004 17:31                      1,581  Inst_repl_hotfix.sql 07-Jan-2005 02:10  2000.80.1000.0    352,828  Isqlw.exe 07-Jan-2005 02:10  2000.80.1000.0     82,492  Itwiz.exe 07-Jan-2005 02:11  2000.80.1000.0     90,692  Msgprox.dll 31-Dec-2004 17:16  8.11.41022.0      226,304  Mssdi98.dll 07-Jan-2005 02:11  2000.80.1000.0     62,024  Odsole70.dll 07-Jan-2005 02:11  2000.80.1000.0     25,144  Opends60.dll 07-Jan-2005 02:10  2000.80.1000.0     57,904  Osql.exe 07-Jan-2005 02:11  2000.80.1000.0    279,104  Pfutil80.dll 31-Dec-2004 17:25                    550,780  Procsyst.sql 31-Dec-2004 17:31                     12,305  Qfe469315.sql 31-Dec-2004 17:31                     19,195  Qfe469571.sql 31-Dec-2004 17:31                      5,157  Qfe472197.sql 07-Jan-2005 02:10  2000.80.1000.0    143,940  Qrdrsvc.exe 07-Jan-2005 02:26                  1,136,072  Replmerg.sql 07-Jan-2005 02:11  2000.80.1000.0    221,768  Replprov.dll 07-Jan-2005 02:11  2000.80.1000.0    307,784  Replrec.dll 07-Jan-2005 00:59  2000.80.1000.0    159,813  Replres.rll 31-Dec-2004 17:31                  1,088,240  Replsys.sql 31-Dec-2004 17:31                    986,603  Repltran.sql 31-Dec-2004 16:49                         55  Repl_uninstall.sql 07-Jan-2005 02:11  2000.80.1000.0    287,304  Rinitcom.dll 07-Jan-2005 02:11  2000.80.1000.0     78,416  Sdiclnt.dll 07-Jan-2005 02:11  2000.80.1000.0     66,112  Semmap.dll 07-Jan-2005 02:11  2000.80.1000.0     57,916  Semnt.dll 07-Jan-2005 02:11  2000.80.1000.0    492,096  Semobj.dll 07-Jan-2005 01:19  2000.80.1000.0    172,032  Semobj.rll 07-Jan-2005 02:11  2000.80.1000.0     53,832  Snapshot.exe 31-Dec-2004 17:25                    117,834  Sp3_serv_uni.sql 07-Jan-2005 02:10  2000.80.1000.0     28,672  Sqlagent.dll 07-Jan-2005 02:11  2000.80.1000.0    311,872  Sqlagent.exe 07-Jan-2005 02:10  2000.80.1000.0    168,001  Sqlakw32.dll 07-Jan-2005 02:11  2000.80.1000.0     33,344  Sqlctr80.dll 07-Jan-2005 02:11  2000.80.1000.0  4,215,360  Sqldmo.dll 07-Jan-2005 02:11                     25,172  Sqldumper.exe 07-Jan-2005 00:51  2000.80.1000.0     28,672  Sqlevn70.rll 07-Jan-2005 02:11  2000.80.1000.0    156,224  Sqlmaint.exe 07-Jan-2005 02:11  2000.80.1000.0    180,792  Sqlmap70.dll 07-Jan-2005 02:11  2000.80.1000.0    188,992  Sqlmmc.dll 07-Jan-2005 01:14  2000.80.1000.0    479,232  Sqlmmc.rll 07-Jan-2005 02:11  2000.80.1000.0    401,984  Sqlqry.dll 07-Jan-2005 02:11  2000.80.1000.0     57,920  Sqlrepss.dll 07-Jan-2005 02:11  2000.80.1000.0  7,716,945  Sqlservr.exe 07-Jan-2005 02:11  2000.80.1000.0    590,396  Sqlsort.dll 07-Jan-2005 02:11  2000.80.1000.0     45,644  Sqlvdi.dll 07-Jan-2005 02:11  2000.80.1000.0    106,588  Sqsrvres.dll 07-Jan-2005 02:11  2000.80.1000.0     33,340  Ssmsgnet.dll 07-Jan-2005 02:11  2000.80.1000.0     33,340  Ssmslpcn.dll 07-Jan-2005 02:11  2000.80.1000.0     33,340  Ssmsqlgc.dll 07-Jan-2005 02:11  2000.80.1000.0     82,492  Ssnetlib.dll 07-Jan-2005 02:11  2000.80.1000.0     25,148  Ssnmpn70.dll 07-Jan-2005 02:11  2000.80.1000.0    123,456  Stardds.dll 07-Jan-2005 02:11  2000.80.1000.0    158,240  Svrnetcn.dll 07-Jan-2005 02:11  2000.80.1000.0     76,416  Svrnetcn.exe 07-Jan-2005 02:11  2000.80.1000.0     49,228  Ums.dll 07-Jan-2005 02:11  2000.80.1000.0     74,304  Xplog70.dll 07-Jan-2005 02:11  2000.80.1000.0     98,872  Xpweb70.dll

SQL Server 2000 64-bit version
  Date         Time   Version          Size       File name      Platform 07-Jan-2005 11:07  2000.80.1000.0      56,832  Dbmslpcn.dll   IA-64 07-Jan-2005 11:07  2000.80.1000.0     528,960  Dtspump.dll    x86 07-Jan-2005 11:07  2000.80.1000.0     185,856  Msgprox.dll    IA-64 31-Dec-2004 19:10  8.11.41022.0       742,912  Mssdi98.dll    IA-64 07-Jan-2005 11:07  2000.80.1000.0     151,040  Odsole70.dll   IA-64 07-Jan-2005 11:08  2000.80.1000.0      27,136  Opends60.dll   IA-64 07-Jan-2005 04:15                      19,880  Opends60.lib 07-Jan-2005 11:07  2000.80.1000.0     148,992  Osql.exe       IA-64 07-Jan-2005 11:07  2000.80.1000.0     353,280  Qrdrsvc.exe    IA-64 07-Jan-2005 11:07  2000.80.1000.0     534,528  Replprov.dll   IA-64 07-Jan-2005 11:07  2000.80.1000.0     769,024  Replrec.dll 07-Jan-2005 11:07  2000.80.1000.0     650,240  Rinitcom.dll   IA-64 07-Jan-2005 11:07  2000.80.1000.0     160,768  Semmap.dll     IA-64 07-Jan-2005 11:07  2000.80.1000.0     132,608  Semnt.dll      IA-64 07-Jan-2005 11:07  2000.80.1000.0      88,576  Snapshot.exe   IA-64 07-Jan-2005 11:07  2000.80.1000.0      10,240  Sqlagent.dll   IA-64 07-Jan-2005 11:07  2000.80.1000.0   1,055,232  Sqlagent.exe   IA-64 07-Jan-2005 11:07  2000.80.1000.0      90,112  Sqlboot.dll    IA-64 07-Jan-2005 11:07  2000.80.1000.0      32,256  Sqlctr80.dll   IA-64 07-Jan-2005 11:07  2000.80.1000.0     812,032  Sqldata.dll    IA-64 07-Jan-2005 11:07  2000.80.1000.0  13,845,504  Sqldmo.dll     IA-64 07-Jan-2005 11:07                      39,936  Sqldumper.exe  IA-64 07-Jan-2005 11:07  2000.80.1000.0     493,568  Sqlmaint.exe 07-Jan-2005 11:07  2000.80.1000.0      23,040  Sqlmap70.dll   IA-64 07-Jan-2005 11:07  2000.80.1000.0     152,064  Sqlrepss.dll 07-Jan-2005 11:08  2000.80.1000.0  25,237,504  Sqlservr.exe 07-Jan-2005 11:07  2000.80.1000.0     616,960  Sqlsort.dll    IA-64 07-Jan-2005 11:07  2000.80.1000.0     120,320  Sqlvdi.dll     IA-64 07-Jan-2005 11:07  2000.80.1000.0     227,328  Sqsrvres.dll   IA-64 07-Jan-2005 11:07  2000.80.1000.0      53,760  Ssmslpcn.dll   IA-64 07-Jan-2005 11:07  2000.80.1000.0      59,904  Ssmsqlgc.dll   IA-64 07-Jan-2005 11:07  2000.80.1000.0     256,000  Ssnetlib.dll   IA-64 07-Jan-2005 11:07  2000.80.1000.0      20,992  Ssnmpn70.dll 07-Jan-2005 11:07  2000.80.1000.0     430,080  Svrnetcn.dll 07-Jan-2005 11:07  2000.80.1000.0     185,856  Svrnetcn.exe 07-Jan-2005 11:07  2000.80.1000.0     183,296  Xplog70.dll 07-Jan-2005 11:07  2000.80.1000.0     187,392  Xpweb70.dll 07-Jan-2005 11:10                       5,058  Hotfix1.inf 31-Dec-2004 19:10  2000.80.962.0       57,904  Osql.exe       x86 31-Dec-2004 19:10  2000.80.760.0      269,824  Sqdedev.dll    IA-64 07-Jan-2005 04:29  2000.80.1000.0     146,432  Replres.rll 07-Jan-2005 04:15  2000.80.1000.0      19,968  Sqlevn70.rll

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

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



MORE INFORMATION
This hotfix is only enabled under trace flag 9063. When trace flag 9063 is enabled, duplicate GROUP BY clauses or DISTINCT keywords will not be removed.

For more information about the naming schema for Microsoft SQL Server updates, click the following article number to view the article in the Microsoft Knowledge Base:

822499 New naming schema for Microsoft SQL Server software update packages

For more information, click the following article number to view the article in the Microsoft Knowledge Base:

824684 Description of the standard terminology that is used to describe Microsoft software updates

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Additional query words: SQL2000

Keywords: kbbug kbfix kbqfe kbhotfixserver KB892392

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