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.
finally to try to fix things i set the optimizer_features_enable=8.1.7
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=rule they 
do run very fast. and have a better explain plan.
 

----------------------------------------------------------------
Please see the official ORACLE-L FAQ: http://www.orafaq.com
----------------------------------------------------------------
To unsubscribe send email to:  oracle-l-request@xxxxxxxxxxxxx
put 'unsubscribe' in the subject line.
--
Archives are at http://www.freelists.org/archives/oracle-l/
FAQ is at http://www.freelists.org/help/fom-serve/cache/1.html
-----------------------------------------------------------------

Other related posts: