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In-Reply-To: <Z3gN3bwUMijyV4I0@ip-10-97-1-34.eu-west-3.compute.internal>
From: Kirill Reshke <reshkekirill@gmail.com>
Date: Thu, 13 Mar 2025 14:00:52 +0500
Message-ID: 
 <CALdSSPh76=ACN=z68oM44ZMgZsQxTTYVF8qvi1F6TGA5Mn6uiQ@mail.gmail.com>
Subject: Re: relfilenode statistics
To: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Cc: Robert Haas <robertmhaas@gmail.com>,
 Michael Paquier <michael@paquier.xyz>,
	pgsql-hackers@lists.postgresql.org
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On Fri, 3 Jan 2025 at 21:18, Bertrand Drouvot
<bertranddrouvot.pg@gmail.com> wrote:

> As mentioned by Andres in [1], relying on the relation OID would not work to
> "recover" the stats because we don't have access to the relation oid during crash
> recovery. So, I'm going to resume working on the "initial" idea (i.e having the
> stats keyed by relfilenode).
>
> [1]: https://www.postgresql.org/message-id/xvetwjsnkhx2gp6np225g2h64f4mfmg6oopkuaiivrpzd2futj%40pflk55su36ho
>

Hmm. While it is true that catalog lookups cannot be performed during
crash recovery, is it really necessary to save and retrieve statistics
after a crash? Given that statistics are permitted to be outdated and
server crashes are anticipated to be infrequent, it looks loke losing
a few analysis runs due to server crashes is acceptable.
In any case, I am totally OK with the relfilenode-based method because
it is generally less restricted (to other postgresql parts e.g. wal-
replay ) and simpler.

Also, this patch needs a rebase;)


-- 
Best regards,
Kirill Reshke