RE: Long Parse Time
Date: Wed, 6 May 2009 20:07:56 -0500
Thanks all for the suggestions everyone. I was pulled into something else today so haven't been able to work on this today.
As for these parameters, like Tanel I doubt they have any impact. Both
are at the default. _optimizer_max_permutations is 2000 and
_optimizer_search_limit is 5.
The parameter _complex_view_merging was set to FALES, changing it to TRUE (the default) did cut the parse time almost in half, down to about 18 seconds but that is still excessive I think. And that was the original query that was hitting all the views. This is what lead me to believe it was s view resolution issue.
Assuming I figure this out, I will let you all know what was going on.
Ric Van Dyke
March 7 - 11, 2010
From: Tanel Poder [mailto:tanel_at_poderc.com]
Sent: Wednesday, May 06, 2009 12:49 PM
To: Brandon.Allen_at_OneNeck.com; Ric Van Dyke; oracle-l_at_freelists.org Subject: RE: Long Parse Time
With a 8-table join this probably isn't the root cause as you've got max 40k join order permutations - that's including all cartesian join orders, which aren't all evaluated by default, _optimizer_search_limit limits the max number of cartesian join orders to be evaluated (120 by default (factorial of 5 = 120)). On the other hand, both these parameters are worth checking. If parsing a 8-table join takes 10s of seconds, it's either a bug or someone has been playing with undocumented parameters.
-- Regards, Tanel Poder http://blog.tanelpoder.com <http://blog.tanelpoder.com/>Received on Wed May 06 2009 - 20:07:56 CDT
From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Allen, Brandon Sent: 06 May 2009 21:44 To: ric.van.dyke_at_hotsos.com; oracle-l_at_freelists.org Subject: RE: Long Parse Time One more thing I forgot to mention - did you check your
_optimizer_max_permutations parameter to make sure somebody didn't
increase it from the default? Another workaround if you're desperate (not generally recommended!) could be to reduce this parameter from the default of 2000. Regards, Brandon
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