From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: Bossart, Nathan <bossartn@amazon.com>
Cc: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Cc: x4mmm@yandex-team.ru <x4mmm@yandex-team.ru>
Cc: a.lubennikova@postgrespro.ru <a.lubennikova@postgrespro.ru>
Cc: hlinnaka@iki.fi <hlinnaka@iki.fi>
Cc: matsumura.ryo@fujitsu.com <matsumura.ryo@fujitsu.com>
Cc: masao.fujii@gmail.com <masao.fujii@gmail.com>
Cc: pgsql-hackers@postgresql.org <pgsql-hackers@postgresql.org>
Subject: Re: archive status ".ready" files may be created too early
Date: Tue, 27 Jul 2021 21:04:58 -0400
Message-ID: <202107280104.ah3afb7d3grg@alvherre.pgsql> (raw)
In-Reply-To: <593A8B65-507E-4C53-9076-5420E429F03B@amazon.com>
On 2021-Feb-19, Bossart, Nathan wrote:
> 0002 adds logic for persisting the last notified segment through
> crashes. This is needed because a poorly-timed crash could otherwise
> cause us to skip marking segments as ready-for-archival altogether.
> This file is only used for primary servers, as there exists a separate
> code path for marking segments as ready-for-archive for standbys.
I'm not sure I understand what's the reason not to store this value in
pg_control; I feel like I'm missing something. Can you please explain?
There were some comments earlier in the thread about the maximum size of
a record. As I recall, you can have records of arbitrary size if you
have COMMIT with a large number of relation invalidation messages being
included in the xlog record, or a large number of XIDs of
subtransactions in the transaction. Spanning several segments is
possible, AFAIU.
--
Álvaro Herrera 39°49'30"S 73°17'W — https://www.EnterpriseDB.com/
"La rebeldía es la virtud original del hombre" (Arthur Schopenhauer)
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To: pgsql-hackers@postgresql.org
Cc: alvherre@alvh.no-ip.org, bossartn@amazon.com, horikyota.ntt@gmail.com, x4mmm@yandex-team.ru, a.lubennikova@postgrespro.ru, hlinnaka@iki.fi, matsumura.ryo@fujitsu.com, masao.fujii@gmail.com
Subject: Re: archive status ".ready" files may be created too early
In-Reply-To: <202107280104.ah3afb7d3grg@alvherre.pgsql>
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