DB2 - Problembeschreibung
Problem IC80663 | Status: Geschlossen |
POOR QUERY PERFORMANCE WHEN STRING HOST VARIABLE OR PARAMETER MARKER IS CAST TO ANOTHER STRING TYPE | |
Produkt: | |
DB2 FOR LUW / DB2FORLUW / 970 - DB2 | |
Problembeschreibung: | |
This APAR improves performance for queries that cast string host variable or parameter marker to another string type. The result only needs to be evaluated once, before this fix, it was evaluated for every row. For example: SELECT * FROM T WHERE GRAPHICCOL = cast( ? as char(10) ) The parameter marker has type CHAR(10), there is an implicit cast to GRAPHIC type. Before this fix, the CHAR to GRAPHIC cast was evaluated for every row of the table instead of once at the beginning of the query. Note that the same thing can occur without explicit host variables or parameter markers when the statement concentrator is enabled, e.g.: SELECT * FROM T WHERE GRAPHICCOL = 'literal' The statement concentrator replaces the string literal with a host variable of type VARCHAR. As above, the VARCHAR host variable is internally cast to GRAPHIC type to match the left hand side of the predicate. | |
Problem-Zusammenfassung: | |
**************************************************************** * USERS AFFECTED: * * ALL * **************************************************************** * PROBLEM DESCRIPTION: * * See Error Description * **************************************************************** * RECOMMENDATION: * * Upgrade to DB2 Version 9.7 Fix Pack 6 or later. * **************************************************************** | |
Local-Fix: | |
N/A | |
verfügbare FixPacks: | |
DB2 Version 9.7 Fix Pack 6 for Linux, UNIX, and Windows | |
Lösung | |
The problem has been fixed in DB2 Version 9.7 Fix Pack 6. | |
Workaround | |
keiner bekannt / siehe Local-Fix | |
Weitere Daten | |
Datum - Problem gemeldet : Datum - Problem geschlossen : Datum - der letzten Änderung: | 04.01.2012 04.03.2013 04.03.2013 |
Problem behoben ab folgender Versionen (IBM BugInfos) | |
9.7.FP6 | |
Problem behoben lt. FixList in der Version | |
9.7.0.6 |