Re: Query Performance with params

Hey Mladen,

> The optimizer in 12.1 is almost completely rewritten, there are bound to be some bugs.

Please tell us more about that. I know that Oracle has completely re-engineered / re-written some transformations like star-transformation in the past but that Oracle has re-written most of the optimizer in 12.1 is new (quite apart from the fact that nothing would justify the time and costs of this).

Thank you.

P.S.: If you mean all of the adaptive features - most of it is happening in the run-time engine code (e.g. statistics collector, etc.) and not in the optimizer code (e.g. inflection point). Dynamic Sampling (in case of SPDs / ADS) is nothing really new - just a "tiny" extension to the existing DS code.  

Best Regards
Stefan Koehler

Independent Oracle performance consultant and researcher Website: http://www.soocs.de
Twitter: _at_OracleSK
Upcoming online seminar: http://tinyurl.com/17-06-13-Shared-Pool-Internals

> Mladen Gogala <gogala.mladen_at_gmail.com> hat am 30. April 2017 um 19:04 geschrieben:
>
> On 04/30/2017 12:42 PM, Thomas Roach wrote:
>
> > > If it's 12.1, then if you are going to set any parameter outside of defaults, it would be optimizer_features_enable back to 11.2.0.4.
> > > That's usually when people throw in the towel if they can't figure it out otherwise.
> >
> >
> > > That will not do much for you. OFE will set up some constants to their 11.2.0.4 values, but the optimizer code will still be the code from
> > > version 12. There are no shortcuts. My usual advice to the customers is to wait for the first major patch set of the version 12.2 to upgrade
> > > and not to upgrade to 12.1. The optimizer in 12.1 is almost completely rewritten, there are bound to be some bugs. Those bugs usually get
> > > polished in the second edition. That was the case with 11.1, although 11.2.0.2 was almost unusable. Somebody on this group has even recently
> > > called 11.2.0.3 a "buggy cesspool". The new versions are so complex and have so many interacting features that it has become extremely hard to
> > > write something that will not be buggy.

--
http://www.freelists.org/webpage/oracle-l