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help / color / mirror / Atom feedFrom: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
To: Michael Paquier <michael@paquier.xyz>
Cc: Andres Freund <andres@anarazel.de>
Cc: Kirill Reshke <reshkekirill@gmail.com>
Cc: Robert Haas <robertmhaas@gmail.com>
Cc: pgsql-hackers@lists.postgresql.org
Subject: Re: relfilenode statistics
Date: Thu, 13 Aug 2026 08:09:25 +0000
Message-ID: <an17tXR24VxWE3w4@bdtpg> (raw)
In-Reply-To: <alCLr8ya-4ojew-x@paquier.xyz>
References: <aRGoGcOdutTHQfpn@paquier.xyz>
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<aUELPdhdcyzTM_8K@paquier.xyz>
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<alCLr8ya-4ojew-x@paquier.xyz>
Hi,
On Fri, Jul 10, 2026 at 03:05:35PM +0900, Michael Paquier wrote:
> - 0003
Thanks for sharing this! Now that the table/index split is (almost) in, let's
focus again on the relfilenode statistics.
> property that I do not wish to keep around is the aggregation of
> counters across rewrites, as the new counters don't make sense once we
> switch to a new relfilenode.
I think we should first agree on this point before looking further at 0003.
As written, the existing pg_stat_all_tables tuple related counters would be reset
by a rewrite.
The concern I see is how these statistics are currently used: relation_needs_vacanalyze()
uses dead_tuples, ins_since_vacuum, and mod_since_analyze for its three tuple based
vacuum or analyze decisions.
For example, a SET TABLESPACE move allocates a new relfilenumber but only copies
the relation’s storage. The previous counters are not transferred, so they are
read as zero for the new relfilenumber. A table that was eligible for vacuum or
analyze before the move may therefore no longer be eligible.
Do you agree that rewrites should not reset these counters?
Regards,
--
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com
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To: pgsql-hackers@postgresql.org
Cc: bertranddrouvot.pg@gmail.com, michael@paquier.xyz, andres@anarazel.de, reshkekirill@gmail.com, robertmhaas@gmail.com, pgsql-hackers@lists.postgresql.org
Subject: Re: relfilenode statistics
In-Reply-To: <an17tXR24VxWE3w4@bdtpg>
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