Re: Re: [External] : Re: Question on gathering System Statistics

My usual recommendation for system statistics is: keep the defaults and if there is a query that has a better execution plan with different values of MREADTIM, SREADTIM, MBRC then the problem is not on system statistics but physical data model. Because there's no good access path and the CBO tries to find the "less worse one" with blind guesses on physical reads. Either make full scan faster (like partitioning) or index access faster (like covering index) and the problem is solved. The right access path should not depend on block access milliseconds because nobody knows if, at execution time, the I/O will be a cache hit in fast memory, or queued in front of a busy disk with many sessions waiting for it. Franck.

On Tue, Feb 2, 2021 at 7:14 PM <rogel_at_web.de> wrote:

>
> Jonathan,
>
> since no one here doubts your authority, you are surely right with that
> (per "argumentum ad verecundiam" ).
> However, my knowledge of Latin, which used to be quite profound in school
> for nine years tells me that you are wrong with that.
>
> Regards
> Matthias
>
> *Gesendet:* Dienstag, 02. Februar 2021 um 18:19 Uhr
> *Von:* "Jonathan Lewis" <jlewisoracle_at_gmail.com>
> *An:* "oracle-l_at_freelists.org" <oracle-l_at_freelists.org>
> *Betreff:* Re: [External] : Re: Question on gathering System Statistics
>
> Splitting hairs here, but:
>
> "argument from authority" is "argumentum ab auctoritate" (e.g. "from
> year of experiance with the CBO I can assure you that gathering systems
> stats is not a good idea ... ").
>
> "argumentum ad verecundiam" is "appeal to authority". (e.g. Nigel Bayliss
> is the PM for the optimizer and he says you don't need to gather system
> stats ...).
>
>
> Regards
> Jonathan Lewis
>
>
> On Tue, 2 Feb 2021 at 15:33, Mladen Gogala <gogala.mladen_at_gmail.com>
> wrote:
>
>> I am one of those guys who has real problems with authority. When I was a
>> kid, I challenged my math teacher to prove the Pythagora theorem and I told
>> her that I don't believe it without proof. She had my parents come to
>> school. That nasty attitude was further reinforced by me getting a Bsc in
>> mathematics few years later. Latin name for the argument from authority is
>> "argumentum ad verecundiam" and is considered to be a logical error since
>> the Roman times. I need some kind of explanation why is that so. I have
>> nothing but respect for Maria, Nigel and Jonathan, but I need some kind of
>> explanation. BTW, my favorite movie of all times is "Life of Brian", which
>> also has something to do with challenging authority.
>>
> -- http://www.freelists.org/webpage/oracle-l

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