DB2 - Problembeschreibung
Problem IC69093 | Status: Geschlossen |
OPTIMIZER UNDER ESTIMATES PAGE FILTERING FOR COLUMN USED IN LOCA L PREDICATE AND ON THE INNER OF NESTED LOOP JOIN. | |
Produkt: | |
DB2 FOR LUW / DB2FORLUW / 970 - DB2 | |
Problembeschreibung: | |
Under limited conditions, the optimizer will over estimate the filtering effect of a join predicate when it is computing the number of pages in an index or a table that will be needed by a Nested Loop Join (NLJOIN) operator. This conditions are: 1) A column with a local predicate applied to it. For example, TEST.YEAR = 2010 2) The column has statistics for which the High2Key statistic is less then the predicate's literal value. For example, the High2Key for TEST.YEAR is '2009'. 3) There is also a join predicate on the same column. For example TEST.YEAR = RESULTS.YEAR 4) The column is included in an index, and that column is being used as a Start/Stop key. Under these conditions, when the optimizer is computing how many pages of the index and table will be touched after the start/stop key has been applied, it will incorrectly compute the filtering effect to indicate that no leaf pages of the index, and no pages of the table will be touched. | |
Problem-Zusammenfassung: | |
Under limited conditions, the optimizer will over estimate the filtering effect of a join predicate when it is computing the number of pages in an index or a table that will be needed by a Nested Loop Join (NLJOIN) operator. This conditions are: 1) A column with a local predicate applied to it. For example, TEST.YEAR = 2010 2) The column has statistics for which the High2Key statistic is less then the predicate's literal value. For example, the High2Key for TEST.YEAR is '2009'. 3) There is also a join predicate on the same column. For example TEST.YEAR = RESULTS.YEAR 4) The column is included in an index, and that column is being used as a Start/Stop key. Under these conditions, when the optimizer is computing how many pages of the index and table will be touched after the start/stop key has been applied, it will incorrectly compute the filtering effect to indicate that no leaf pages of the index, and no pages of the table will be touched. | |
Local-Fix: | |
update the High2Key to be >= the literal value in the local predicate | |
verfügbare FixPacks: | |
DB2 Version 9.7 Fix Pack 3 for Linux, UNIX, and Windows | |
Lösung | |
apar fixed >= v97 fpk3 | |
Workaround | |
update the High2Key to be >= the literal value in the local predicate | |
Weitere Daten | |
Datum - Problem gemeldet : Datum - Problem geschlossen : Datum - der letzten Änderung: | 08.06.2010 23.09.2010 23.09.2010 |
Problem behoben ab folgender Versionen (IBM BugInfos) | |
9.7.FPk3 | |
Problem behoben lt. FixList in der Version | |
9.7.0.3 | |
9.7.0.3 |