Re: Best course to understand why a bad plan is chosen by optimizer

Thanks Mladen for the response.
Yes , i have tried to pretty much everything under the sun with the statistics, histograms, dynamic sampling.

On Thu, Sep 12, 2019 at 9:52 PM Mladen Gogala <gogala.mladen_at_gmail.com> wrote:

>
> On 9/12/19 9:43 PM, kunwar singh wrote:
> > Hi Listers,
> > Silly question :)
> >
> > Is there any Oracle guru who give course on this specific topic and
> > goes much in depth.
> >
> > Not looking for course on sql tuning. I am able to tune the query in
> > most cases, it is the optimizer decisions for many queries in a new
> > version upgrade(11g to 12.1.0.2).. which are giving me some headaches
> > as many applications we support generate queries dynamically and
> > statistics optimization is the farthest i am able to go to get good
> > plans.
> > Cannot use SPM options due to dynamic nature of sqls generation.
> >
> >
> Have you tried with different statistics options? System statistics,
> OPTIMIZER_DYNAMIC_SAMPLING, proper histograms and alike? I found out
> long time ago that collecting statistics properly usually gives me good
> performance for 99% of the queries. The best way to tune is not to do
> it at all.
>
>
> --
> Mladen Gogala
> Database Consultant
> Tel: (347) 321-1217
>
> --
> http://www.freelists.org/webpage/oracle-l
>
>
>

-- 
Cheers,
Kunwar

--
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