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DB2 - Problembeschreibung

Problem IC68939 Status: Geschlossen

PERFORMANCE ISSUE WHEN CAST AROUND LITERAL FOR BIT DATA IS PRESENT

Produkt:
DB2 FOR LUW / DB2FORLUW / 970 - DB2
Problembeschreibung:
This problem happens ONLY WHEN CAST for BIT DATA and only when 
it is on one side and not another and only when literals. 
DB2 generate non-optimal plans because BIT_STRING function is 
injected and it prevents certain optimization logic. Please 
consider the following examples: 
 
CAST(x'00' AS CHAR(1) FOR BIT DATA) = CAST(x'01' AS CHAR(1) FOR 
BIT DATA) 
- will perform well 
 
x'00'    = x'01' 
- will perform well 
 
CAST(x'00' AS CHAR(1) FOR BIT DATA) = x'01' 
- here PERFROMANCE is BAD.
Problem-Zusammenfassung:
**************************************************************** 
* USERS AFFECTED:                                              * 
* All                                                          * 
**************************************************************** 
* PROBLEM DESCRIPTION:                                         * 
* This problem happens ONLY WHEN CAST for BIT DATA and         * 
* onlywhenit is on one side and not another and only when      * 
* literals.DB2 generate non-optimal plans because BIT_STRING   * 
* functionisinjected and it prevents certain optimization      * 
* logic. Pleaseconsider the following examples:CAST(x'00' AS   * 
* CHAR(1) FOR BIT DATA) = CAST(x'01' AS CHAR(1)FORBIT DATA)-   * 
* will perform wellx'00'    = x'01'- will perform              * 
* wellCAST(x'00' AS CHAR(1) FOR BIT DATA) = x'01'- here        * 
* PERFROMANCE is BAD.                                          * 
**************************************************************** 
* RECOMMENDATION:                                              * 
* Upgrade to DB2 9.7 FP3                                       * 
****************************************************************
Local-Fix:
rewrite the statement in the following manner 
CAST(x'00' AS CHAR(1) FOR BIT DATA) = CAST(x'01' AS CHAR(1) FOR 
BIT DATA)
verfügbare FixPacks:
DB2 Version 9.7 Fix Pack 3 for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 3a for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 4 for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 5 for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 6 for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 7 for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 8 for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 9 for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 9a for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 10 for Linux, UNIX, and Windows

Lösung
Problem was first fixed in Version 9.7 Fix Pack 3
Workaround
keiner bekannt / siehe Local-Fix
Weitere Daten
Datum - Problem gemeldet    :
Datum - Problem geschlossen :
Datum - der letzten Änderung:
03.06.2010
19.10.2010
19.10.2010
Problem behoben ab folgender Versionen (IBM BugInfos)
9.7.FP3
Problem behoben lt. FixList in der Version
9.7.0.3 FixList
9.7.0.3 FixList