RE: Long Parse Time

  • From: "Tanel Poder" <tanel@xxxxxxxxxx>
  • To: <Brandon.Allen@xxxxxxxxxxx>, <ric.van.dyke@xxxxxxxxxx>, <oracle-l@xxxxxxxxxxxxx>
  • Date: Wed, 6 May 2009 22:49:15 +0300

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.
Tanel Poder <>  


From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx]
On Behalf Of Allen, Brandon
Sent: 06 May 2009 21:44
To: ric.van.dyke@xxxxxxxxxx; oracle-l@xxxxxxxxxxxxx
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.







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