From: Peter Eisentraut <peter.eisentraut@enterprisedb.com>
To: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: Amit Langote <amitlangote09@gmail.com>
Cc: Laurenz Albe <laurenz.albe@cybertec.at>
Cc: Pg Hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: cataloguing NOT NULL constraints
Date: Wed, 14 Sep 2022 22:03:50 +0200
Message-ID: <bac841ed-b86d-e3c2-030d-02a3db067307@enterprisedb.com> (raw)
In-Reply-To: <20220909175813.vu5kd2m67mrrqkjv@alvherre.pgsql>
References: <20220909175813.vu5kd2m67mrrqkjv@alvherre.pgsql>
On 09.09.22 19:58, Alvaro Herrera wrote:
> There were a lot more problems in that submission than I at first
> realized, and I had to rewrite a lot of code in order to fix them. I
> have fixed all the user-visible problems I found in this version, and
> reviewed the tests results more carefully so I am now more confident
> that behaviourally it's doing the right thing; but
Reading through the SQL standard again, I think this patch goes a bit
too far in folding NOT NULL and CHECK constraints together. The spec
says that you need to remember whether a column was defined as NOT NULL,
and that the commands DROP NOT NULL and SET NOT NULL only affect
constraints defined in that way. In this implementation, a constraint
defined as NOT NULL is converted to a CHECK (x IS NOT NULL) constraint
and the original definition is forgotten.
Besides that, I think that users are not going to like that pg_dump
rewrites their NOT NULL constraints into CHECK table constraints.
I suspect that this needs a separate contype for NOT NULL constraints
that is separate from CONSTRAINT_CHECK.
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To: pgsql-hackers@postgresql.org
Cc: peter.eisentraut@enterprisedb.com, alvherre@alvh.no-ip.org, amitlangote09@gmail.com, laurenz.albe@cybertec.at, pgsql-hackers@lists.postgresql.org
Subject: Re: cataloguing NOT NULL constraints
In-Reply-To: <bac841ed-b86d-e3c2-030d-02a3db067307@enterprisedb.com>
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