Feedback-ID: ia2694551:Fastmail
Date: Sat, 4 May 2024 11:20:32 +0200
From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: Justin Pryzby <pryzby@telsasoft.com>
Cc: Robert Haas <robertmhaas@gmail.com>, 
	Kyotaro Horiguchi <horikyota.ntt@gmail.com>, pgsql-hackers@lists.postgresql.org, 
	Alexander Lakhin <exclusion@gmail.com>, Dmitry Koval <d.koval@postgrespro.ru>
Subject: Re: pg17 issues with not-null contraints
Message-ID: <202405040920.2rg4mmjgv3ch@alvherre.pgsql>
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On 2024-May-03, Justin Pryzby wrote:

> But if it's created with LIKE:
> postgres=# CREATE TABLE t1 (LIKE t);
> postgres=# ALTER TABLE t ATTACH PARTITION t1 DEFAULT ;
> 
> ..one also sees:
> 
> Not-null constraints:
>     "t1_i_not_null" NOT NULL "i"

Hmm, I think the problem here is not ATTACH; the not-null constraint is
there immediately after CREATE.  I think this is all right actually,
because we derive a not-null constraint from the primary key and this is
definitely intentional.  But I also think that if you do CREATE TABLE t1
(LIKE t INCLUDING CONSTRAINTS) then you should get only the primary key
and no separate not-null constraint.  That will make the table more
similar to the one being copied.

Does that make sense to you?

-- 
Álvaro Herrera               48°01'N 7°57'E  —  https://www.EnterpriseDB.com/
"Estoy de acuerdo contigo en que la verdad absoluta no existe...
El problema es que la mentira sí existe y tu estás mintiendo" (G. Lama)