From: Julien Rouhaud <rjuju123@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Bruce Momjian <bruce@momjian.us>
Cc: Magnus Hagander <magnus@hagander.net>
Cc: Fujii Masao <masao.fujii@oss.nttdata.com>
Cc: PostgreSQL Developers <pgsql-hackers@lists.postgresql.org>
Subject: Re: compute_query_id and pg_stat_statements
Date: Mon, 26 Apr 2021 01:32:06 +0800
Message-ID: <20210425173206.wch7fv3afi5hrxlt@nol> (raw)
In-Reply-To: <2000204.1619371023@sss.pgh.pa.us>
References: <35457b09-36f8-add3-1d07-6034fa585ca8@oss.nttdata.com>
<20210424152220.GL7629@momjian.us>
<CABUevEx4YQi42MwaMq3Bo09=mBqfjUqtkp5NUZpnQ0HdX+5+Hw@mail.gmail.com>
<20210424170908.GM7629@momjian.us>
<1709439.1619286231@sss.pgh.pa.us>
<20210425082251.pokyapaxlzdr7k2t@nol>
<1934987.1619365195@sss.pgh.pa.us>
<20210425161742.jczixbwvojlsf2wx@nol>
<2000204.1619371023@sss.pgh.pa.us>
On Sun, Apr 25, 2021 at 01:17:03PM -0400, Tom Lane wrote:
> Julien Rouhaud <rjuju123@gmail.com> writes:
> > On Sun, Apr 25, 2021 at 11:39:55AM -0400, Tom Lane wrote:
> >> I agree repeated warnings would be bad news. I was wondering if we could
> >> arrange a single warning at the time pg_stat_statements is preloaded into
> >> the postmaster. In this way, if you tried to use a configuration file
> >> that used to work, you'd hopefully get some notice about why it no longer
> >> does what you want. Also, if you are preloading pg_stat_statements, it
> >> seems reasonable to assume that you'd like the global value of the flag
> >> to be "on", even if there are use-cases for transiently disabling it.
>
> > What about people who wants to use pg_stat_statements but are not ok with our
> > query_id heuristics and use a third-party plugin for that?
>
> They're still going to want the GUC set to something other than "off",
> no?
They will want compute_query_id to be off. And they actually will *need* that,
as we recommend third-party plugins computing alternative query_id to error out
if they see a that a query_id has already been generated, to avoid any problem
if compute_query_id is being temporarily toggled. That's what I did in the POC
plugin for external query_id at [1].
> In any case it's just a one-time log message, so it's not likely
> to be *that* annoying.
In that case it should be phrased in a way that makes it clear that
pg_stat_statements can work without enabling compute_query_id, something like:
"compute_query_id is disabled. This module won't track any activity unless you
configured a third-party extension that computes query identifiers"
[1] https://github.com/rjuju/pg_queryid/blob/master/pg_queryid.c#L172
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To: pgsql-hackers@postgresql.org
Cc: rjuju123@gmail.com, tgl@sss.pgh.pa.us, bruce@momjian.us, magnus@hagander.net, masao.fujii@oss.nttdata.com, pgsql-hackers@lists.postgresql.org
Subject: Re: compute_query_id and pg_stat_statements
In-Reply-To: <20210425173206.wch7fv3afi5hrxlt@nol>
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