Date: Wed, 13 Apr 2022 17:55:18 -0700
From: Andres Freund <andres@anarazel.de>
To: "David G. Johnston" <david.g.johnston@gmail.com>
Cc: Kyotaro Horiguchi <horikyota.ntt@gmail.com>,
	Melanie Plageman <melanieplageman@gmail.com>,
	Justin Pryzby <pryzby@telsasoft.com>,
	Thomas Munro <thomas.munro@gmail.com>,
	PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: shared-memory based stats collector - v70
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Hi,

On 2022-04-13 16:56:45 -0700, David G. Johnston wrote:
> On Wed, Apr 13, 2022 at 4:34 PM David G. Johnston <
> david.g.johnston@gmail.com> wrote:
> Sorry, apparently this "2000-01-01" behavior only manifests after crash
> recovery on v15 (didn't check v14); after a clean initdb on v15 I got the
> same initdb timestamp.

> Feels like we should still report the "end of crash recovery timestamp" for
> these instead of 2000-01-01 (which I guess is derived from 0) if we are not
> willing to produce null (and it seems other parts of the system using these
> stats assumes non-null).

Yes, that's definitely not correct. I see the bug (need to call
pgstat_reset_after_failure(); in pgstat_discard_stats()). Stupid, but
easy to fix - too fried to write a test tonight, but will commit the fix
tomorrow.

Thanks for catching!

Greetings,

Andres Freund