Re: Planning counters in pg_stat_statements (using pgss_store)

On 2020/04/09 22:31, Julien Rouhaud wrote:
> On Thu, Apr 9, 2020 at 5:59 AM Fujii Masao <masao(dot)fujii(at)oss(dot)nttdata(dot)com> wrote:
>>
>>
>>
>> On 2020/04/08 18:31, Julien Rouhaud wrote:
>>> On Wed, Apr 08, 2020 at 05:37:27PM +0900, Fujii Masao wrote:
>>>>
>>>>
>>>> On 2020/04/03 16:26, Julien Rouhaud wrote:
>>>>> On Thu, Apr 02, 2020 at 01:04:28PM -0700, legrand legrand wrote:
>>>>>> Fujii Masao-4 wrote
>>>>>>> On 2020/04/01 18:19, Fujii Masao wrote:
>>>>>>>
>>>>>>> Finally I pushed the patch!
>>>>>>> Many thanks for all involved in this patch!
>>>>>>>
>>>>>>> As a remaining TODO item, I'm thinking that the document would need to
>>>>>>> be improved. For example, previously the query was not stored in pgss
>>>>>>> when it failed. But, in v13, if pgss_planning is enabled, such a query is
>>>>>>> stored because the planning succeeds. Without the explanation about
>>>>>>> that behavior in the document, I'm afraid that users will get confused.
>>>>>>> Thought?
>>>>>>
>>>>>> Thank you all for this work and especially to Julian for its major
>>>>>> contribution !
>>>>>
>>>>>
>>>>> Thanks a lot to everyone! This was quite a long journey.
>>>>>
>>>>>
>>>>>> Regarding the TODO point: Yes I agree that it can be improved.
>>>>>> My proposal:
>>>>>>
>>>>>> "Note that planning and execution statistics are updated only at their
>>>>>> respective end phase, and only for successfull operations.
>>>>>> For exemple executions counters of a long running SELECT query,
>>>>>> will be updated at the execution end, without showing any progress
>>>>>> report in the interval.
>>>>>> Other exemple, if the statement is successfully planned but fails in
>>>>>> the execution phase, only its planning statistics are stored.
>>>>>> This may give uncorrelated plans vs calls informations."
>>>>
>>>> Thanks for the proposal!
>>>>
>>>>> There are numerous reasons for lack of correlation between number of planning
>>>>> and number of execution, so I'm afraid that this will give users the false
>>>>> impression that only failed execution can lead to that.
>>>>>
>>>>> Here's some enhancement on your proposal:
>>>>>
>>>>> "Note that planning and execution statistics are updated only at their
>>>>> respective end phase, and only for successful operations.
>>>>> For example the execution counters of a long running query
>>>>> will only be updated at the execution end, without showing any progress
>>>>> report before that.
>>>>
>>>> Probably since this is not the example for explaining the relationship of
>>>> planning and execution stats, it's better to explain this separately or just
>>>> drop it?
>>>>
>>>> What about the attached patch based on your proposals?
>>>>
>>>
>>> Thanks Fuji-san, it looks perfect to me!
>>
>> Thanks for the check! Pushed!
>
> Thanks a lot Fuji-san!
>
> For the record, the commit is available, but I didn't receive the
> usual mail, and it's also not present in the archives apparently:
> https://www.postgresql.org/list/pgsql-committers/since/202004090000/
> (although Amit's latest commit was delivered as expected).

Yes.

> Given your previous discussion with Magnus, I'm assuming that your
> address is now allowed to post for a year. I'm not sure what went
> wrong here, so I'm adding Magnus in Cc.

Thanks! I also reported the issue in pgsql-www.

Regards,

--
Fujii Masao
Advanced Computing Technology Center
Research and Development Headquarters
NTT DATA CORPORATION