Date: Fri, 25 Feb 2022 08:47:22 -0800
From: Andres Freund <andres@anarazel.de>
To: Magnus Hagander <magnus@hagander.net>
Cc: PostgreSQL Developers <pgsql-hackers@lists.postgresql.org>
Subject: Re: Add parameter jit_warn_above_fraction
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Hi,

On 2022-02-25 17:28:41 +0100, Magnus Hagander wrote:
> On Fri, Feb 25, 2022 at 5:20 PM Andres Freund <andres@anarazel.de> wrote:
> > On 2022-02-25 16:16:01 +0100, Magnus Hagander wrote:
> > > This patch adds a configuration parameter jit_warn_above_fraction that
> > > will cause a warning to be logged if the fraction of time spent on
> > > doing JIT is bigger than the specified one. For example, this can be
> > > used to track down those cases where JIT ends up taking 90% of the
> > > query runtime because of bad estimates...
> >
> > Hm. Could it make sense to do this as a auto_explain feature?
> 
> It could be. But I was looking for something a lot more "light weight"
> than having to install an extension. But yes, if we wanted to, we
> could certainly change jit_warn_above_fraction to be
> auto_explain.log_min_jit_fraction or something like that, and do
> basically the same thing.  But then, we could also have
> log_min_duration_statement be part of auto_explain instead, so it's
> all about where to draw the line :)

I guess it feels a tad on the "too narrow/specific" side of things for the
general code. We don't have log_min_duration_{parsing,planning,execution}
either.  But I also get it. So I just wanted to raise it ;)

Greetings,

Andres Freund