| From: | Jeff Janes <jeff(dot)janes(at)gmail(dot)com> |
|---|---|
| To: | Jean-Christophe Boggio <postgresql(at)thefreecat(dot)org> |
| Cc: | "pgsql-performance(at)lists(dot)postgresql(dot)org" <pgsql-performance(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: Strange "actual time" in simple CTE |
| Date: | 2023-12-04 03:15:27 |
| Message-ID: | CAMkU=1zLViLfA=gBdK-+h94TwHLVdqgEWTADkVQ4c5WQEfX=Aw@mail.gmail.com |
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| Lists: | pgsql-performance |
On Sat, Dec 2, 2023 at 11:50 AM Jean-Christophe Boggio <
postgresql(at)thefreecat(dot)org> wrote:
> Hello,
>
> I am trying to optimize a complex query and while doing some explains, I
> stumbled upon this :
>
> CTE cfg
> -> Result (cost=2.02..2.03 rows=1 width=25) (actual
> time=7167.478..7167.481 rows=1 loops=1)
> ...
> How can this take 7 seconds?
>
> This really looks like an artefact (maybe in relation to the JIT compiler?)
>
>
Exactly. The time taking to do the JIT compilations gets measured in
non-intuitive places in the plan. I'm guessing that that is what is going
on here, especially since the time separately reported at the end of the
plan for JIT so closely matches this mysterious time. Just turn JIT off, I
doubt it doing you any good anyway.
Cheers,
Jeff
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