DB2 - Problembeschreibung
Problem IC68474 | Status: Geschlossen |
THE DB2 OPTIMIZER MAY MIS-ESTIMATE THE JOIN CARDINALITY OF AN IN-TO-JOIN TRANSFORMATION IN A DPF ENVIRONMENT | |
Produkt: | |
DB2 FOR LUW / DB2FORLUW / 970 - DB2 | |
Problembeschreibung: | |
The DB2 query optimizer may mis-estimate the join cardinality of an in-to-join transformation in a DPF environment, when the table that the IN predicate applies to is hash partitioned across two or more database partition, and the SQL statement includes predicates that bound the table access a single database partition. For example, consider a table T hash partitioned on column A. When optimizing the an SQL statement such as the following: select * from T where A = ? and B in (?,?) the optimizer recognizes that the predicate "A=?" will only exist on a single database partition since the table is hash partitioned on A; that is, it recognizes that the table is bound to a single database partition. In such a scenario, if the optimizer considers an in-to-join transformation for the predicate "B in (?,?)", it may mis-estimate the cardinality which could lead to a less-than-optimal access plan. Users Affected: DPF only | |
Problem-Zusammenfassung: | |
THE DB2 OPTIMIZER MAY MIS-ESTIMATE THE JOIN CARDINALITY OF AN IN-TO-JOIN TRANSFORMATION IN A DPF ENVIRONMENT | |
Local-Fix: | |
n/a | |
verfügbare FixPacks: | |
DB2 Version 9.7 Fix Pack 3 for Linux, UNIX, and Windows | |
Lösung | |
Workaround | |
keiner bekannt / siehe Local-Fix | |
Weitere Daten | |
Datum - Problem gemeldet : Datum - Problem geschlossen : Datum - der letzten Änderung: | 09.05.2010 13.10.2010 13.10.2010 |
Problem behoben ab folgender Versionen (IBM BugInfos) | |
Problem behoben lt. FixList in der Version | |
9.7.0.3 | |
9.7.0.3 |