Re: Performance adjustment and query optimization

I believe I've read somewhere that having automatic performance adjustment
on can have an adverse effect on query optimization. Because when the
query optimizer runs it ignores the previous optimization analysis and
reanalyzes if the memory changes because the memory available is taken
into the calculation. So, if you have like a million sql statements in a
loop (canned vendor package) each time it loops it may have to reanalyze
because the memory changes, well maybe not every loop because the adjuster
is not quite that fast to recalculate.

I have a PMR open with IBM and they are looking at Job Watcher data and
now have moved on into SQL plan cache but while waiting on that I wanted
to explore other things.

Also, on a closely related note, does having your paging set *CALC vs
*FIXED affect query optimization?
See WRKSYSSTS and WRKSHRPOOL


Rob Berendt
--
IBM Certified System Administrator - IBM i 6.1
Group Dekko
Dept 1600
Mail to: 2505 Dekko Drive
Garrett, IN 46738
Ship to: Dock 108
6928N 400E
Kendallville, IN 46755
http://www.dekko.com

--
This is the Midrange Systems Technical Discussion (MIDRANGE-L) mailing list
To post a message email: MIDRANGE-L@xxxxxxxxxxxx
To subscribe, unsubscribe, or change list options,
visit: http://lists.midrange.com/mailman/listinfo/midrange-l
or email: MIDRANGE-L-request@xxxxxxxxxxxx
Before posting, please take a moment to review the archives
at http://archive.midrange.com/midrange-l.

Please contact support@xxxxxxxxxxxx for any subscription related
questions.