FIX: Query performance may be slower if the query contains both a GROUP BY clause and a DISTINCT keyword on the same column (892392)


The information in this article applies to:

  • Microsoft SQL Server 2000 Desktop Engine (MSDE)
  • 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 64 bit
  • Microsoft SQL Server 2000 Enterprise Edition 64-bit
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
back to the top

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

back to the top

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.

back to the top

RESOLUTION

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.

back to the top

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 "The product does not have a prerequisite update installed" error message when you try to install a SQL Server 2000 post-Service Pack 3 hotfix

back to the top

Restart information

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

back to the top

Registry information

You do not have to change the registry.

back to the top

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.
back to the top

STATUS

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" 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

back to the top
Modification Type:MinorLast Reviewed:6/1/2006
Keywords:kbbug kbfix kbHotfixServer kbQFE KB892392 kbAudITPRO kbAudDeveloper
©2004 Microsoft Corporation. All rights reserved.