Date: Wed, 18 Aug 2021 13:45:23 -0400
From: "alvherre@alvh.no-ip.org" <alvherre@alvh.no-ip.org>
To: "Bossart, Nathan" <bossartn@amazon.com>
Cc: Kyotaro Horiguchi <horikyota.ntt@gmail.com>,
	"x4mmm@yandex-team.ru" <x4mmm@yandex-team.ru>,
	"a.lubennikova@postgrespro.ru" <a.lubennikova@postgrespro.ru>,
	"hlinnaka@iki.fi" <hlinnaka@iki.fi>,
	"matsumura.ryo@fujitsu.com" <matsumura.ryo@fujitsu.com>,
	"masao.fujii@gmail.com" <masao.fujii@gmail.com>,
	"pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Subject: Re: archive status ".ready" files may be created too early
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On 2021-Aug-18, alvherre@alvh.no-ip.org wrote:

> I realize this means there's a contradiction with my previous argument,
> in that synchronous transaction commit calls XLogWrite at some point, so
> we *are* putting the client-connected backend in charge of creating the
> notify files.  However, that only happens on transaction commit, where
> we already accept responsibility for the WAL flush, not on each
> individual XLOG record insert; also, the WAL writer will take care of it
> sometimes, for transactions that are long-enough lived.

Eh.  I just said WAL writer will sometimes do it, and that's true
because it'll occur in XLogBackgroundFlush.  But upthread I wimped out
of having WAL writer call NotifySegmentsReadyForArchive() and instead
opined to give responsibility to bgwriter.  However, thinking about it
again, maybe it does make sense to have walwriter do it too directly.
This causes no harm to walwriter's time constraints, since *it will have
to do it via XLogBackgroundFlush anyway*.

-- 
Álvaro Herrera              Valdivia, Chile  —  https://www.EnterpriseDB.com/