From: Tom Lane <tgl@sss.pgh.pa.us>
To: "Shulgin, Oleksandr" <oleksandr.shulgin@zalando.de>
cc: Simon Riggs <simon@2ndquadrant.com>, Robert Haas <robertmhaas@gmail.com>,
 Pavel Stehule <pavel.stehule@gmail.com>,
 Tomas Vondra <tomas.vondra@2ndquadrant.com>,
 PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Subject: Re: On-demand running query plans using auto_explain and signals
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Comments: In-reply-to "Shulgin, Oleksandr" <oleksandr.shulgin@zalando.de>
 message dated "Thu, 15 Oct 2015 11:16:01 +0200"
Date: Thu, 15 Oct 2015 09:42:47 -0400
Message-ID: <32603.1444916567@sss.pgh.pa.us>
Precedence: bulk
Sender: pgsql-hackers-owner@postgresql.org

"Shulgin, Oleksandr" <oleksandr.shulgin@zalando.de> writes:
> I was thinking about this and what seems to be the biggest problem is when
> to actually turn the feature on.  It seems unlikely that someone will want
> to enable it unconditionally.  Enabling per-backend also doesn't seem to be
> a good approach because you don't know if the next query you'd like to look
> at is going to run in this exact backend.

Check.

> What might be actually usable is poking pg_stat_statements for queryid to
> decide if we need to do explain (and possibly analyze).

Hm, interesting thought.

> Does this make sense to you?  Does this make a good argument for merging
> pg_stat_statements and auto_explain into core?

I'd say more that it's a good argument for moving this feature out to
one of those extensions, or perhaps building a third extension that
depends on both of those.  TBH, none of this stuff smells to me like
something that ought to be in core.

			regards, tom lane


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