Microsoft KB Archive/833406

= FIX: Cardinality estimates for literals that are outside the histogram range are very low =

Article ID: 833406

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 Personal Edition
 * Microsoft SQL Server 2000 Enterprise Edition
 * Microsoft SQL Server 2000 Enterprise 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 #: 470474 (SHILOH_BUGS)



SYMPTOMS
The Microsoft SQL Server query optimizer may underestimate the cardinality of a predicate of the form column = constant when all the following conditions are true:
 * Statistics exist for the specified column.
 * The constant that is specified in the predicate is outside the range of the histogram. To determine whether the constant is outside the range, run the DBCC SHOW_STATISTICS statement, and then note when the value of the constant is less than the first RANGE_HI_KEY entry or greater than the last entry of the output.
 * The rowmodctr value for the index is not zero. This value indicates that inserts, updates, or deletes have occurred since the statistics were last updated, and a significant part of the modified rows have statistics values that are outside the current histogram boundaries.

When this problem occurs, SQL Server may not generate an optimal execution plan for your query, and poor performance may result.

These symptoms are fairly common for tables that have parent-child relationships when all the following conditions are true:
 * The parent table has a primary key on a column that is an increasing key value, such as an identity column or a datetime value that reflects the insert time.
 * The foreign key in the child table references the primary key column from the parent table.



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 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.   Date         Time   Version            Size    File name 31-May-2003 18:45  2000.80.818.0      78,400  Console.exe 28-Oct-2003 04:21  2000.80.873.0     315,968  Custtask.dll 02-Oct-2003 20:59  2000.80.867.0      33,340  Dbmslpcn.dll 25-Apr-2003 02:12                    786,432  Distmdl.ldf 25-Apr-2003 02:12                  2,359,296  Distmdl.mdf 30-Jan-2003 01:55                        180  Drop_repl_hotfix.sql 12-Sep-2003 03:26  2000.80.859.0   1,905,216  Dtspkg.dll 26-Aug-2003 20:16  2000.80.854.0     528,960  Dtspump.dll 23-Jun-2003 22:40  2000.80.837.0   1,557,052  Dtsui.dll 23-Jun-2003 22:40  2000.80.837.0     639,552  Dtswiz.dll 24-Apr-2003 02:51                    747,927  Instdist.sql 03-May-2003 01:56                      1,581  Inst_repl_hotfix.sql 08-Feb-2003 06:40  2000.80.765.0      90,692  Msgprox.dll 01-Apr-2003 02:07                      1,873  Odsole.sql 05-Apr-2003 01:46  2000.80.800.0      62,024  Odsole70.dll 07-May-2003 20:41  2000.80.819.0      25,144  Opends60.dll 02-Apr-2003 21:48  2000.80.796.0      57,904  Osql.exe 02-Apr-2003 23:15  2000.80.797.0     279,104  Pfutil80.dll 04-Aug-2003 18:17                    550,780  Procsyst.sql 12-Sep-2003 00:37                     12,305  Qfe469315.sql 22-May-2003 22:57                     19,195  Qfe469571.sql 06-Sep-2003 01:36                  1,090,932  Replmerg.sql 06-Sep-2003 07:18  2000.80.858.0     221,768  Replprov.dll 06-Sep-2003 07:18  2000.80.858.0     307,784  Replrec.dll 06-Sep-2003 00:00                  1,087,150  Replsys.sql 13-Aug-2003 16:28                    986,603  Repltran.sql 22-Oct-2003 00:08  2000.80.871.0      57,916  Semnt.dll 29-Jul-2003 20:13  2000.80.819.0     492,096  Semobj.dll 31-May-2003 18:27  2000.80.818.0     172,032  Semobj.rll 05-Aug-2003 21:06                    127,884  Sp3_serv_uni.sql 01-Jun-2003 01:01  2000.80.818.0   4,215,360  Sqldmo.dll 07-Apr-2003 17:44                     25,172  Sqldumper.exe 19-Mar-2003 18:20  2000.80.789.0      28,672  Sqlevn70.rll 27-Sep-2003 04:42  2000.80.865.0     180,792  Sqlmap70.dll 03-Sep-2003 02:56  2000.80.857.0     188,992  Sqlmmc.dll 02-Sep-2003 23:03  2000.80.857.0     479,232  Sqlmmc.rll 22-Oct-2003 00:08  2000.80.871.0     401,984  Sqlqry.dll 08-Feb-2003 06:40  2000.80.765.0      57,920  Sqlrepss.dll 03-Dec-2003 23:52  2000.80.891.0   7,606,353  Sqlservr.exe 25-Jul-2003 21:44  2000.80.845.0     590,396  Sqlsort.dll 08-Feb-2003 06:40  2000.80.765.0      45,644  Sqlvdi.dll 02-Oct-2003 20:59  2000.80.867.0      33,340  Ssmslpcn.dll 01-Jun-2003 01:01  2000.80.818.0      82,492  Ssnetlib.dll 01-Jun-2003 01:01  2000.80.818.0      25,148  Ssnmpn70.dll 28-Oct-2003 04:21  2000.80.873.0     123,456  Stardds.dll 01-Jun-2003 01:01  2000.80.818.0     158,240  Svrnetcn.dll 31-May-2003 18:59  2000.80.818.0      76,416  Svrnetcn.exe 30-Apr-2003 23:52  2000.80.816.0      45,132  Ums.dll 02-Jul-2003 00:19  2000.80.834.0      98,816  Xpweb70.dll Note Because of file dependencies, the most recent hotfix or feature that contains these files may also contain additional files.



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.



MORE INFORMATION
To explicitly enable this hotfix, you must turn on trace flag 9185. If you experience the problem that is described in the &quot;Symptoms&quot; section, you may also experience a similar problem with joins. Trace flag 9205 is used to enable the join-related hotfix. We recommend that you enable both of these trace flags together. For additional information about the problem with joins, click the following article number to view the article in the Microsoft Knowledge Base:

319173 FIX: Cardinality estimates are too low when value is outside histogram

For additional 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

Keywords: kbbug kbfix kbqfe kbsqlserv2000presp4fix kbhotfixserver KB833406

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