DB2 - Problembeschreibung
Problem IC81676 | Status: Geschlossen |
IMPROVE ACCURACY OF FILTER FACTOR ESTIMATE FOR NON-CORRELATED EXISTS CLAUSE | |
Produkt: | |
DB2 FOR LUW / DB2FORLUW / 950 - DB2 | |
Problembeschreibung: | |
The filter factor of a non-correlated EXISTS clause, such as: ... where exists ( select 1 from table1 A, table2 B where A.key = b.key and A.col2 = 'XYZ') ... May be more or less filtering depending on the results of the subselect in the exists. This APAR will improve the accuracy of the resulting filter factor of the EXISTS clause. For example, you may see the exists subselect show up in the explain plan as a FILTER with an estimated cardinality of 0.5 instead of a more accurate estimate for the probability a row will be returned from the subselect: /---------+ 0.5 FILTER | /-------+--------\ 1 40 TBSCAN ^NLJOIN | | 1 /-----+------\ TABFNC: SYSIBM 40 1 GENROW TBSCAN IXSCAN Q4 | | 1000 1000 TABLE: DB2INST1 INDEX: DB2INST1 TABLE1 TABLE2_PK Q2 Q1 | |
Problem-Zusammenfassung: | |
**************************************************************** * USERS AFFECTED: * * ALL * **************************************************************** * PROBLEM DESCRIPTION: * * See Error Description * **************************************************************** * RECOMMENDATION: * * Upgrade to DB2 9.5 FP10 or subsequent fix pack. * **************************************************************** | |
Local-Fix: | |
Use SELECTIVITY CLAUSE or Optimizer Profile to change the overall access plan. | |
Lösung | |
Problem First Fixed in DB2 Version 9.5 Fix Pack 10 | |
Workaround | |
keiner bekannt / siehe Local-Fix | |
Bug-Verfolgung | |
Vorgänger : APAR is sysrouted TO one or more of the following: IC84002 IC87888 IC87903 IC87923 Nachfolger : | |
Weitere Daten | |
Datum - Problem gemeldet : Datum - Problem geschlossen : Datum - der letzten Änderung: | 27.02.2012 06.11.2012 06.11.2012 |
Problem behoben ab folgender Versionen (IBM BugInfos) | |
9.5.FP10 | |
Problem behoben lt. FixList in der Version | |
9.5.0.10 |