RE: Varying plans on different nodes

  • From: "Mark W. Farnham" <mwf@xxxxxxxx>
  • To: <fairlie_r@xxxxxxxxx>, "'Oracle-L'" <oracle-l@xxxxxxxxxxxxx>
  • Date: Thu, 7 Jun 2007 06:34:19 -0400

Without at all trying to be comprehensive, different nodes means different


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.







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



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