From: | torikoshia <torikoshia(at)oss(dot)nttdata(dot)com> |
---|---|
To: | Fujii Masao <masao(dot)fujii(at)oss(dot)nttdata(dot)com>, Tatsuro Yamada <tatsuro(dot)yamada(dot)tf(at)nttcom(dot)co(dot)jp> |
Cc: | Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>, legrand legrand <legrand_legrand(at)hotmail(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Is it useful to record whether plans are generic or custom? |
Date: | 2020-12-04 06:03:25 |
Message-ID: | 65fbc50741c558bae5470e15ef33c4c7@oss.nttdata.com |
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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.
>
Yeah.
ISTM now that creating pg_stat_statements_xxx views
both for generic andcustom plans is better than my PoC patch.
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.
Yamada-san,
Do you think it's effective just distinguish between generic
and custom plans?
Regards,
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