Hello All, We are moving from version 11.2.0.4 to version12.1.0.2.0 of
Oracle. We can't go to the latest versions(like 19C/18C) because of certain
application dependencies which are running on this database. Team is
suggesting to keep the optimizer_feature_enable as it was for
existing version i.e. 11.2.0.4, as because there are issues/bugs for
version 12.1.0.2.0.
So I wanted to check with experts here , if it's really so and have such
a bad experience with OFE- 12.1.0.2.0 and we must keep the optimizer
feature at 11.2.0.4 even if the database version would be 12.1.0.2?
For information, We do use a lot of Global temporary tables in our
application code, but then we are thinking these will get the benefit of
the private session level stats on OFE- 12.1 and it won't happen such if we
keep the OFE at 11.2. Even if we don't change the code to gather stats on
the GTT immediately during migration , then that will still keep on using
dynamic sampling(in absence of session level stats) as it used to happen on
version 11.2. And gradually we will change our code to gather session level
stats in application code where estimation is going bad impacting execution
path.
Regards
Pap
