DB2 - Problembeschreibung
Problem IT01796 | Status: Geschlossen |
OPTIMIZER COMPUTES INCORRECT CARDINALITY ESTIMATE IN PRESENCE OF STATISTICAL VIEW WITH A PREDICATE THAT HAS AN EXPRESSION | |
Produkt: | |
DB2 FOR LUW / DB2FORLUW / A50 - DB2 | |
Problembeschreibung: | |
The optimizer might compute an incorrect cardinality estimate in an access plan for a SQL statement on which a statistical view is eligible, if the following conditions are true: 1) There is a statview ( sv1 ), whose SELECT list contains expression column. 2) There is another statview ( sv2 ), which contains a predicate involving the same expression. For example, consider the following statistical views: create view sv1(x) as (select c1+5 from t1); create view sv2(y) as (select c1 from t1 where c2+1 < 2 and c1+5 = 5); Please note the expression 'c1+5'. It is the output column of sv1 and it is also used in predicate for sv2. In this case, the optimizer might compute an incorrect cardinality estimate for the following SQL statement: select * from t1 where c1+5=5 and c2+1<2; The explain plan ( i.e. db2exfmt output ) of above SQL may show the following diagnostic messages: Diagnostic Details: EXP0233I The predicate "Q4.C1 + 5 = 5" contains an expression matching the statistical view column "SCHEMA1.SV1" Diagnostic Details: EXP0147W The following statistical view was used by the optimizer to estimate cardinalities: "SCHEMA1"."SV2". | |
Problem-Zusammenfassung: | |
**************************************************************** * USERS AFFECTED: * * ALL * **************************************************************** * PROBLEM DESCRIPTION: * * See Error Description * **************************************************************** * RECOMMENDATION: * * Upgrade to DB2 Version 10.5 Fix Pack 4 * **************************************************************** | |
Local-Fix: | |
verfügbare FixPacks: | |
DB2 Cancun Release 10.5.0.4 (also known as Fix Pack 4) for Linux, UNIX, and Windows | |
Lösung | |
Upgrade to DB2 Version 10.5 Fix Pack 4 | |
Workaround | |
keiner bekannt / siehe Local-Fix | |
Weitere Daten | |
Datum - Problem gemeldet : Datum - Problem geschlossen : Datum - der letzten Änderung: | 14.05.2014 27.10.2014 27.10.2014 |
Problem behoben ab folgender Versionen (IBM BugInfos) | |
Problem behoben lt. FixList in der Version | |
10.5.0.4 |