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 | |
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 | |
9.7.0.3 |