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Problem IC65989
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Status: Geschlossen |
QUERY PERFORMANCE PROBLEM WITH A JOIN PREDICATE THAT INVOLVES A CASE STATEMENT THAT RETURNS A MIX OF CONSTANT AND COLUMN VALUES |
| Produkt: |
DB2 FOR LUW / DB2FORLUW / 970 - DB2 |
| Problembeschreibung: |
The CASE statement used to generate a value that was applied as
a start/stop key in an index access, but due to the rewrite of
the CASE-based predicate to a series of "AND" and "OR"
pedicates, the rewritten predicate is applied as a SARG
predicate on an IXSCAN or TBSCAN |
| Problem-Zusammenfassung: |
The CASE statement used to generate a value that was applied as
a start/stop key in an index access, but due to the rewrite of
the CASE-based predicate to a series of "AND" and "OR"
pedicates, the rewritten predicate is applied as a SARG
predicate on an IXSCAN or TBSCAN |
| Local-Fix: |
workaround is to replace one of the simple column expressions or
constants in the 'THEN' portion of the WHEN clause with a more
complex expression, or if the CASE does not return a NULL, wrap
the CASE in a coalesce function (i.e. join_col = coalesce( CASE
... END, 1)) |
| verfügbare FixPacks: |
DB2 Version 9.7 Fix Pack 2 for Linux, UNIX, and Windows
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 9a for Linux, UNIX, and Windows
DB2 Version 9.7 Fix Pack 8 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 |
workaround is to replace one of the simple column expressions or
constants in the 'THEN' portion of the WHEN clause with a more
complex expression, or if the CASE does not return a NULL, wrap
the CASE in a coalesce function (i.e. join_col = coalesce( CASE
... END, 1)) |
| Workaround |
workaround is to replace one of the simple column expressions or
constants in the 'THEN' portion of the WHEN clause with a more
complex expression, or if the CASE does not return a NULL, wrap
the CASE in a coalesce function (i.e. join_col = coalesce( CASE
... END, 1)) |
| Weitere Daten |
Datum - Problem gemeldet :
Datum - Problem geschlossen :
Datum - der letzten Änderung:
| 02.02.2010
13.05.2010
13.05.2010 |
| Problem behoben ab folgender Versionen (IBM BugInfos) |
|
| Problem behoben lt. FixList in der Version |
| 9.7.0.2
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