Re: cardinality feedback in 19c

Mohamed,

Thanks for the feedback.
Interesting oddity.

Regards
Jonathan Lewis

On Tue, 27 Apr 2021 at 14:16, Mohamed Houri <mohamed.houri_at_gmail.com> wrote:

>
>
> Jonathan
>
>
>
> They are all after newly added and conventionally loaded partitions on
> which statistics for conventional DML is used. The application is then
> re-running fresh statistics on the newly added partition every 2 hours. Now
> those queries are back to their good plan. But I would like to avoid such a
> case of execution plan switch. The first optimized execution plan (the one
> on which Oracle realizes that it has a cardinality misestimates and marked
> the underlying cursor for a new re-optimization) was a very good one J
>
> So, now thinking whether canceling statistics feedback on those queries
> will help to avoid this plan switch
>
> Best regards
>
> Mohamed
>
> Le mar. 27 avr. 2021 à 15:04, Jonathan Lewis <jlewisoracle_at_gmail.com> a
> écrit :
>
>> Mohamed,
>>
>> Have you spotted any common pattern to the 6 unlucky queries?
>>
>> Regards
>> Jonathan Lewis
>>
>>
>> On Tue, 27 Apr 2021 at 13:53, Mohamed Houri <mohamed.houri_at_gmail.com>
>> wrote:
>>
>>> Hello Sayan
>>>
>>> Thanks for your answer. It confirms why I haven't experienced any
>>> performs pain with cardinality feedback in all the 19c databases I have to
>>> deal with. Until today where 6 critical queries changed their execution
>>> plan from a good one to a very bad one and the non-sharing reason was
>>> USE_FEEDBACK_STATS
>>>
>>> Best regards
>>> Mohamed
>>>
>>>
>
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>
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>
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