Horton

Re: Is it useful to record whether plans are generic or custom?

Tatsuro Yamada <tatsuro.yamada.tf@nttcom.co.jp>

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From: Tatsuro Yamada <tatsuro.yamada.tf@nttcom.co.jp>
To: Fujii Masao <masao.fujii@oss.nttdata.com>, Pavel Stehule <pavel.stehule@gmail.com>, torikoshia <torikoshia@oss.nttdata.com>
Cc: legrand legrand <legrand_legrand@hotmail.com>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Date: 2021-01-27T22:53:18Z
Lists: pgsql-hackers 
On 2020/12/04 14:29, Fujii Masao wrote:
> 
> On 2020/11/30 15:24, Tatsuro Yamada wrote:
>> Hi Torikoshi-san,
>>
>>
>>> In this patch, exposing new columns is mandatory, but I think
>>> it's better to make it optional by adding a GUC something
>>> like 'pgss.track_general_custom_plans.
>>>
>>> I also feel it makes the number of columns too many.
>>> Just adding the total time may be sufficient.
>>
>>
>> I think this feature is useful for DBA. So I hope that it gets
>> committed to PG14. IMHO, many columns are Okay because DBA can
>> select specific columns by their query.
>> Therefore, it would be better to go with the current design.
> 
> But that design may waste lots of memory. No? For example, when
> plan_cache_mode=force_custom_plan, the memory used for the columns
> for generic plans is not used.
> 
> Regards,


Sorry for the super delayed replay.
I don't think that because I suppose that DBA uses plan_cache_mode if
they faced an inefficient execution plan. And the parameter will be used
as a session-level GUC parameter, not a database-level.


Regards,
Tatsuro Yamada

Commits

  1. Add generic_plans and custom_plans fields into pg_prepared_statements.