Re: Missing query plan for auto_explain.

From: Maxim Boguk <maxim(dot)boguk(at)gmail(dot)com>
To: Matheus Martin <matheus(dot)martin(at)voidbridge(dot)com>
Cc: pgsql-general(at)postgresql(dot)org
Subject: Re: Missing query plan for auto_explain.
Date: 2022-09-09 21:05:27
Message-ID: CAK-MWwQ3sD_s2HYePjOOHeEeO3fxQPpUzxrhcUEaVyTC+xh4LQ@mail.gmail.com
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On Thu, Sep 8, 2022 at 1:18 PM Matheus Martin <matheus(dot)martin(at)voidbridge(dot)com>
wrote:

> We do have JIT enabled `jit=on` with `jit_above_cost=100000`.
>
> I am sorry but I don't quite understand what role JIT plays in
> this situation with `auto_explain`. Could you please elaborate on that?
>
>
In your log - time spent during the execution stage (where auto-exlain can
help) but during the bind/planning stage (e.g. generation of plan).
So you have a problem not with slow query execution, but with slow query
planning, so autoexplain cannot help in that case.
JIT is one possible explanation of planning stage slowdown.

Can you run explain (analyze, costs, buffers, timing) of your query?
And check how long the planning stage took and check if JIT was used or not
(and how much time spent during JIT if it had been used).

--
Maxim Boguk
Senior Postgresql DBA
https://dataegret.com/

Phone UA: +380 99 143 0000
Phone AU: +61 45 218 5678

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