Hi,
Oracle 8.0.5
AIX 4.3.3
I have improved the response time of one of my 8 table join queries by
increasing optimizer_search_limit from the default 5 to 8. At the value of 8
the plan changes and has made a 10 min query run in under 5 seconds. The
optimizer is set to CHOOSE with the statistics up to date and a sample size
of 20%. This is a third party application and I don't have access to the
source code to add hints. The value of optimizer_max_permutations has been
left at 80000.
I know that this makes the optimizer now check 8!=40320 permutations instead
of 5!=120 permutations. I expect the parse time to increase but does anyone
have any experience as to the performance impact that this may have? Any
horror stories?
Thanks in advance.
Steve Wilkes
_____________
Oracle DBA
npower
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