RE: Long Parse Time

  • From: "Ric Van Dyke" <ric.van.dyke@xxxxxxxxxx>
  • To: "Tanel Poder" <tanel@xxxxxxxxxx>, <Brandon.Allen@xxxxxxxxxxx>, <oracle-l@xxxxxxxxxxxxx>
  • 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

Hotsos Enterprises

-----------------------

 

Hotsos Symposium 

March 7 - 11, 2010 

Be there.

 

 

________________________________

From: Tanel Poder [mailto:tanel@xxxxxxxxxx] 
Sent: Wednesday, May 06, 2009 12:49 PM
To: Brandon.Allen@xxxxxxxxxxx; Ric Van Dyke; oracle-l@xxxxxxxxxxxxx
Subject: RE: Long Parse Time

 

Brandon,

 

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/>  

         

        
________________________________


        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.

         

        Regards,

        Brandon

         

         

         

        
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