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

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

From: Tatsuro Yamada <tatsuro.yamada.tf@nttcom.co.jp>
To: Kyotaro Horiguchi <horikyota.ntt@gmail.com>, torikoshia@oss.nttdata.com
Cc: masao.fujii@oss.nttdata.com, pavel.stehule@gmail.com, legrand_legrand@hotmail.com, pgsql-hackers@postgresql.org
Date: 2021-01-27T23:02:02Z
Lists: pgsql-hackers
Horiguchi-san,

On 2020/12/04 15:37, Kyotaro Horiguchi wrote:
>> And I'm also struggling with the following.
>>
>> | However, I also began to wonder how effective it would be to just
>> | distinguish between generic and custom plans.  Custom plans can
>> | include all sorts of plans. and thinking cache validation, generic
>> | plans can also include various plans.
>>
>> | Considering this, I'm starting to feel that it would be better to
>> | not just keeping whether generic or cutom but the plan itself as
>> | discussed in the below thread.
> 
> FWIW, that seems to me to be like some existing extension modules,
> pg_stat_plans or pg_store_plans..  The former is faster but may lose
> plans, the latter doesn't lose plans but slower.  I feel that we'd
> beter consider simpler feature if we are intendeng it to be a part of
> a contrib module,

There is also pg_show_plans.
Ideally, it would be better to able to track all of the plan changes by
checking something view since Plan Stability is important for DBA when
they use PostgreSQL in Mission-critical systems.
I prefer that the feature will be released as a contrib module. :-D

Regards,
Tatsuro Yamada
  




Commits

  1. Add generic_plans and custom_plans fields into pg_prepared_statements.