Re: Priority of profile baseline patch

Thank you so much Mohamed.

*"When generating this execution plan, all things being equal, Oracle will use the set of hints contained in the SQL Profile or the SQL patch. It is only when the execution plan has been generated that the SPM finally comes into play."*

As you mentioned above and aso from the diagram , it's only when the plan evaluated using either sql patch/stored outline/sqlprofile/hints etc matches one of the sql_handle with accepted=YES and enabled=YES, then that plan will be in use. But in case none of the accepted=yes and enabled=yes sql plan baseline matches with the incoming parsed plan which is generated using sql patch/hints/sql profile, then that new plan will be added to the sql plan baseline list with enabled=yes but accepted=NO, and will be in use. And in this case isn't it incorrect for Oracle to use a plan which has not been accepted by us in the sql plan baseline? Am I missing anything here?And if this is true , then there is no guarantee that the enabled and accepted baselines are always going to be the only plans to be in use by the sql optimizer.

My thought initially was , if the incoming parsed plan(which has came through the profile/patch/hints etc..) doesn't match with any of the baselines( accepted=yes and enabled=yes) baselines then , it should go back and use one of the baselines( accepted=yes and enabled=yes) having lower cost only.

On Fri, Dec 17, 2021 at 3:17 PM Mohamed Houri <mohamed.houri_at_gmail.com> wrote:

> Hello
>
> *In other words the sql profile or sql patch helps to create new plans
> based on the embedded hints however presence of baseline with
> accepted +enabled flag as 'YES' is always going to rule at the end. Correct
> if my understanding is wrong here?*
>
> The underlined part is incorrect
>
> If you look at the picture I designed in this article
>
>
> https://hourim.wordpress.com/2015/10/01/oracle-optimizer-and-spm-plan-interaction/
>
> You will realize that the presence of an SPM has *no influence on the
> ordinary work of the CBO*. Initially, Oracle will produce its execution
> plan ignoring the presence or absence of an SPM.
>
> When generating this execution plan, all things being equal, Oracle will
> use the set of hints contained in the SQL Profile or the SQL patch. *It
> is only when the execution plan has been generated that the SPM finally
> comes into play.*
>
> And what exactly will this SPM do?
>
> It will simply ensure that only the execution plan contained in the SPM
> baseline will be used regardless of how this plan has been generated, via
> SQL Profile, via SQL patch, or without any of those two features.
>
> Of course, this insurance against a bad surprise(a non-desired execution
> plan) is only possible if the plan in the SPM is reproducible at the time
> of the execution of the request.
>
> Hope this is clear
>
> Best regards
>
> Mohamed Houri
>
>
>
> Le ven. 17 déc. 2021 à 05:18, Pap <oracle.developer35_at_gmail.com> a écrit :
>
>> Thank you so much Andy.
>>
>> If I get it correct, it's the sql profile(which is generally a
>> combination of opt_estimate hints) which oracle will use to evaluate the
>> plans but it's ultimately the sqlplan baselines (which must be in
>> accepted+enabled) state which is going to be used finally.
>>
>> And in scenarios where we use technique to manually create sql profile by
>> passing exact outline hints (but not with opt_etsimate hints) i.e. using
>> procedure dbms_sqltune.import_sql_profile where we have ability to pass
>> the exact full query outline hints which restricts the execution path to
>> one. In those cases it will mostly fix the exact one execution path for the
>> query no matter how many times it parses. And in the presence of such a sql
>> profile , if the sql plan baseline has exactly the same path
>> enabled+accepted that is going to be used or else it's going to be
>> completely discarded and the priority will be given to the baseline which
>> is in accepted+enabled state. (And the discarded plan i.e the parsed plan
>> using sql profile may be added a new baseline to the list with accepted
>> flag as NO). Which means sql plan baseline having enabled+accepted flag
>> as "YES" will take the precedence always irrespective of sql profile/sq
>> patch etc. Is this understanding correct?
>> Or
>> In other words the sql profile or sql patch helps to create new plans
>> based on the embedded hints however presence of baseline with
>> accepted +enabled flag as 'YES' is always going to rule at the end. Correct
>> if my understanding is wrong here?
>>
>> On Fri, Dec 17, 2021 at 1:53 AM Andy Klock <andy_at_klockmail.com> wrote:
>>
>>> Hi Laurentiu,
>>>
>>> ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
>>> On Thursday, December 16th, 2021 at 3:08 PM, Pap <
>>> oracle.developer35_at_gmail.com> wrote:
>>>
>>> So in cases where the SQL profile or SQL patch has some hints (say FTS
>>> on tab1) which is exactly opposite than that of the one in SQL plan
>>> baseline(say index access for tab1). In that scenario will oracle follow
>>> profile/patch or the baseline path?
>>>
>>>
>>> If a cursor has "accepted" baselines, then that is typically what the
>>> CBO is going to prefer. When there are multiple accepted plans, then the
>>> CBO will pick the plan with the lowest cost. For cursors that also have a
>>> SQL Profile, then those hints and opt_estimates are applied which may
>>> affect the cost of the baseline plans that the CBO will pick.
>>>
>>> Maria wrote a nice article about it [1] in 2012 which I think is still
>>> relevant, but often when you have cursors with lots of baselines, SQL
>>> Profiles, and patches it's time to fix the stats or change the code :)
>>>
>>> Andy K
>>>
>>> [1]
>>> https://blogs.oracle.com/optimizer/post/what-is-the-difference-between-sql-profiles-and-sql-plan-baselines
>>>
>>
>
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>
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