Re: Varying plans on different nodes

  • From: "Alex Gorbachev" <gorbyx@xxxxxxxxx>
  • To: mwf@xxxxxxxx, fairlie_r@xxxxxxxxx, Oracle-L <oracle-l@xxxxxxxxxxxxx>
  • Date: Thu, 7 Jun 2007 08:54:51 -0400

Mark,

I bet it's consistent and not just the first parse as Failie was able
to reparse it with 10053 trace.

Fairlie,
Did you try diff on two 10053 trace? There must be something else
that's different and difficult to catch for an eye. Also, any chance
that node have differences in one-off patches?

Alex


On 6/7/07, Mark W. Farnham <mwf@xxxxxxxx> wrote:
Without at all trying to be comprehensive, different nodes means different
instances.



Parameters could be different, what is in cache could be different, AWR
could have different accumulations of various things, and the parameter
values of a given sql that was parsed first on a given instance could be
different. Anything that the optimizer at the release level you are at can
use that is specific to an instance rather than a database is a candidate
for examination.



If one plan is "good enough" for all predicate values, then your solution is
likely to be some variety of plan stabilization for that sql.



My first guess is that the initial parse on the two different "nodes" had
wildly different predicate values so that the "bad" plan was actually less
costly for that particular set.



Regards,



mwf



  _____

From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx]
On Behalf Of fairlie rego
Sent: Wednesday, June 06, 2007 10:13 PM
To: Oracle-L
Subject: Varying plans on different nodes



<snip>




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Best regards,
Alex Gorbachev

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