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SLOW PERFORMANCE DUE TO POOR COSTING OF PAGE RANGE REDUCTION ON QUERY ON
PARTITIONED TABLESPACE
Release 710 : UK02167 available 05/05/09 (1000)
Release 810 : UK02168 available 05/05/09 (1000)
Poor query performance may occur for queries on a partitioned
table space where page range reduction is used. Specifically,
when multiple page ranges exist, the cost estimation to
process each page range is calculated incorrectly, leading
to an overly optimistic cost for page range reduction. This
access path could then be chosen even if there are better
access paths that exist.
.
Due to internal SPA issue with our PQ - UQ - PK - UK transition,
PK00552 was rebuilt with PQ97866 into UK02167 (V7) and
UK02168 (V8). Please WATCH for these PTFs on this issue.
Slow query performance in V7 may occur for NPI (nonpartitioned
index) index access with partition screening. Incorrect cost
estimation is used when multiple partition ranges are qualified.
A different problem in V8 may occur for NPI index access with
partition screening and list prefetch.
Additional Keywords: SQLACCESSPATH SQLPERFORMANCE PERFM
SQLPRUNING
P.S. Please pass my address to anyone interested in DB2 HOTLINE - thank you.
With kind regards
Michael Dewert, Software GroupTechnical Sales DB2
