Horton

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

Fujii Masao <masao.fujii@oss.nttdata.com>

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From: Fujii Masao <masao.fujii@oss.nttdata.com>
To: Tatsuro Yamada <tatsuro.yamada.tf@nttcom.co.jp>, 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: 2020-12-04T05:29:35Z
Lists: pgsql-hackers 

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,

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

Commits

  1. Add generic_plans and custom_plans fields into pg_prepared_statements.