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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
DB2 Version 9.7 Fix Pack 3a for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 4 for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 5 for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 6 for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 7 for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 8 for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 9a for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 9 for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 10 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 FixList
9.7.0.3 FixList