Feedback-ID: ia2694551:Fastmail
Date: Mon, 14 Apr 2025 23:33:03 +0200
From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: jian he <jian.universality@gmail.com>,
	Pg Hackers <pgsql-hackers@lists.postgresql.org>,
 Tender Wang <tndrwang@gmail.com>
Subject: Re: not null constraints, again
Message-ID: <202504142133.qeqgu7ujm4ie@alvherre.pgsql>
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On 2025-Apr-14, Tom Lane wrote:

> The patch I propose there seems to prevent this, but I wonder if we
> shouldn't look closer into why it's failing in the first place.
> I would not have expected that adding pg_constraint rows implies
> stronger locks than what ALTER ADD PRIMARY KEY was using before,
> and I suspect that doing so will cause more problems than just
> breaking parallel restore.

I wasn't aware of this side effect.  I'll investigate this in more
depth.  I suspect it might be a bug in the way we run through ALTER
TABLE for the primary key.

-- 
Álvaro Herrera         PostgreSQL Developer  —  https://www.EnterpriseDB.com/
"Los cuentos de hadas no dan al niño su primera idea sobre los monstruos.
Lo que le dan es su primera idea de la posible derrota del monstruo."
                                                   (G. K. Chesterton)