RE: Issues with queries after upgrade,
- From: "Nelson, Allan" <anelson@xxxxxxxxxxx>
- To: oracle-l@xxxxxxxxxxxxx
- Date: Wed, 30 Jun 2004 10:20:34 -0500
The optimizer is better (read different) in 9.2 verses 8.1.7. Using the
rule optimizer biases you toward using nested loops and indexes. You
can do that in other ways if you want to use the hint approach. For
instance you can use a nested loop hint. You should read up on this to
get the details. The 9.2 optimizer has options that the 8.1.7 didn't.
I'm assuming that your test and dev environments did not have enough
similarity to production to produce the same results.
Allan
-----Original Message-----
=46rom: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Fuad Arshad
Sent: Wednesday, June 30, 2004 10:08 AM
To: oracle-l@xxxxxxxxxxxxx
Subject: Issues with queries after upgrade,
We've upgraded to 9.2.0.4 on one of our high volume databases. As usual
everything was fine in dev and test but high volume queries have started
to break .
one of the problems that we founf the the unnest_subq turned off.
=66inally to try to fix things i set the optimizer_features_enable=3D8.1.7
but some of our explain plans have changed wherein the query was using
a sort is not now using concatenation.
any ideas thoughts on why this is happening.
strangely enough if i run some of the queires using optimizer_goal=3Drule
they do run very fast. and have a better explain plan.
=20
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