Feedback-ID: id4a34324:Fastmail
Date: Tue, 12 Jul 2022 19:18:22 -0700
From: Andres Freund <andres@anarazel.de>
To: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Cc: melanieplageman@gmail.com, pryzby@telsasoft.com,
	alvherre@alvh.no-ip.org, magnus@hagander.net,
	pgsql-hackers@postgresql.org, lukas@fittl.com,
	thomas.munro@gmail.com
Subject: Re: pg_stat_bgwriter.buffers_backend is pretty meaningless (and
 more?)
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Hi,

On 2022-07-13 11:00:07 +0900, Kyotaro Horiguchi wrote:
> I imagined to use B_INVALID as a kind of "default" partition, which
> accepts all unknown backend types.

There shouldn't be any unknown backend types. Something has gone wrong if we
get far without a backend type set.


> We can just ignore that values but then we lose the clue for malfunction of
> stats machinery. I thought that that backend-type as the sentinel for
> malfunctions.  Thus we can emit logs instead.
> 
> I feel that the stats machinery shouldn't stop the server as possible,
> or I think it is overreaction to abort for invalid values that can be
> easily coped with.

I strongly disagree. That just ends up with hard to find bugs.

Greetings,

Andres Freund