DB2 - Problembeschreibung
Problem IC73907 | Status: Geschlossen |
THE OPTIMIZER MAY CHOOSE A SUB-OPTIMAL ACCESS PLAN FOR SQL USING SUB-SELECT & PLACE HOLDER VARIABLE. | |
Produkt: | |
DB2 FOR LUW / DB2FORLUW / 970 - DB2 | |
Problembeschreibung: | |
The optimizer may choose a sub-optimal access plan for an SQL statement which uses an IN and a place holder variable as part of the FROM clause. e.g. select ... from tab1, tab2 where tab1.COLA=tab2.COLA and tab1.COLB IN (?,?,?,...); If there is an index with t1.COLB as the leading column in the key, the optimizer can consider an in-to-join transformation of the IN predicate shown in the WHERE clause. If the access of tab1 is on the inner of a NLJN, the optimizer might consider a plan with a TEMP over the inner access that might be beneficial for the in-to-join access on the inner. In general, this is a good option to consider but when there are statement place holders, the cardinality estimates cannot always be accurate. | |
Problem-Zusammenfassung: | |
**************************************************************** * USERS AFFECTED: * * All Platforms * **************************************************************** * PROBLEM DESCRIPTION: * * The optimizer may choose a sub-optimal access plan for an * * SQL * * statement which uses an IN and a place holder variable as * * part * * of the FROM clause. * **************************************************************** * RECOMMENDATION: * * Upgrade to DB2 V9.7 Fix Pack 5. * **************************************************************** | |
Local-Fix: | |
dbset DB2_EXTENDED_IN2JOIN=NLJN_TEMP_OFF | |
verfügbare FixPacks: | |
DB2 Version 9.7 Fix Pack 5 for Linux, UNIX, and Windows | |
Lösung | |
This problem was first fixed in DB2 V9.7 Fix Pack 5. | |
Workaround | |
keiner bekannt / siehe Local-Fix | |
Weitere Daten | |
Datum - Problem gemeldet : Datum - Problem geschlossen : Datum - der letzten Änderung: | 17.01.2011 27.12.2011 27.12.2011 |
Problem behoben ab folgender Versionen (IBM BugInfos) | |
9.7.FP5 | |
Problem behoben lt. FixList in der Version | |
9.7.0.5 |