Date: Mon, 5 Oct 2020 19:58:42 -0300
From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Bruce Momjian <bruce@momjian.us>, Julien Rouhaud <rjuju123@gmail.com>,
	torikoshia <torikoshia@oss.nttdata.com>,
	Atsushi Torikoshi <atorik@gmail.com>,
	Tatsuro Yamada <tatsuro.yamada.tf@nttcom.co.jp>,
	Robert Haas <robertmhaas@gmail.com>,
	Tomas Vondra <tomas.vondra@2ndquadrant.com>,
	Michael Paquier <michael@paquier.xyz>,
	Evgeny Efimkin <efimkin@yandex-team.ru>,
	PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: Feature improvement: can we add queryId for
 pg_catalog.pg_stat_activity view?
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On 2020-Oct-05, Tom Lane wrote:

> FWIW, I think this proposal is a mess.  I was willing to hold my nose
> and have a queryId field in the internal Query struct without any solid
> consensus about what its semantics are and which extensions get to use it.
> Exposing it to end users seems like a bridge too far, though.  In
> particular, I'm afraid that that will cause people to expect it to have
> consistent values across PG versions, or even just across architectures
> within one version.

I wonder if it would help to purposefully change the computation so that
it is not -- for instance, hash the system_identifier as initial value.
Then users would be forced to accept that it'll change as soon as it
migrates to another server or is upgraded to a new major version.