Horton

Re: Feature improvement: can we add queryId for pg_catalog.pg_stat_activity view?

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Bruce Momjian <bruce@momjian.us>, Julien Rouhaud <rjuju123@gmail.com>, Michael Paquier <michael@paquier.xyz>, Alvaro Herrera <alvherre@alvh.no-ip.org>, torikoshia <torikoshia@oss.nttdata.com>, Atsushi Torikoshi <atorik@gmail.com>, Tatsuro Yamada <tatsuro.yamada.tf@nttcom.co.jp>, Tomas Vondra <tomas.vondra@2ndquadrant.com>, Evgeny Efimkin <efimkin@yandex-team.ru>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2020-10-12T18:26:15Z
Lists: pgsql-hackers 
Robert Haas <robertmhaas@gmail.com> writes:
> I don't really understand how a version number helps. It's not like
> there is going to be a v2 that is in all ways better than v1. If there
> are different algorithms here, they are going to be customized for
> different needs.

Yeah, I agree --- a version number is the wrong way to think about this.
It's gonna be more like algorithm foo versus algorithm bar versus
algorithm baz, where each one is better for a specific set of use-cases.
Julien already noted the point about hashing object OIDs versus object
names; one can easily imagine disagreeing with pg_stat_statement's
choices about ignoring values of constants; other properties of statements
might be irrelevant for some use-cases; and so on.

I'm okay with moving pg_stat_statement's existing algorithm into core as
long as there's a way for extensions to override it.  With proper design,
that would allow extensions that do override it to coexist with
pg_stat_statements (thereby redefining the latter's idea of which
statements are "the same"), which is something that doesn't really work
nicely today.

			regards, tom lane

Commits

  1. Clarify description of pg_stat_statements columns

  2. Fix wording in description of pg_stat_statements.toplevel

  3. Mention that toplevel is part of pg_stat_statements key.

  4. adjust query id feature to use pg_stat_activity.query_id

  5. Update copyright for 2021

  6. Take the statistics collector out of the loop for monitoring backends'