From: Peter Eisentraut <peter@eisentraut.org>
To: Tom Lane <tgl@sss.pgh.pa.us>
To: David G. Johnston <david.g.johnston@gmail.com>
Cc: elionescu@yahoo.com <elionescu@yahoo.com>
Cc: pgsql-docs@lists.postgresql.org <pgsql-docs@lists.postgresql.org>
Subject: Re: incorrect (incomplete) description for "alter domain"
Date: Wed, 31 Jul 2024 07:22:30 +0200
Message-ID: <beafea49-f28d-4953-90fe-bf759161ef9d@eisentraut.org> (raw)
In-Reply-To: <2596729.1722266261@sss.pgh.pa.us>
References: <172225092461.915373.6103973717483380183@wrigleys.postgresql.org>
<CAKFQuwbZ3KDq3CtG0qtw7gVT4EWgmD8XFMktEFcruVs98ihCSw@mail.gmail.com>
<2585954.1722265086@sss.pgh.pa.us>
<2596729.1722266261@sss.pgh.pa.us>
On 29.07.24 17:17, Tom Lane wrote:
> I wrote:
>> I think the page is technically correct, but I'm inclined to duplicate
>> this text from the CREATE DOMAIN page:
>
>> where domain_constraint is:
>> [ CONSTRAINT constraint_name ]
>> { NOT NULL | NULL | CHECK (expression) }
>
>> rather than making readers go look that up.
>
> Actually, there *is* a bug in the description, because experimentation
> shows that CREATE DOMAIN accepts NULL in this syntax (as advertised)
> but ALTER DOMAIN does not. We could alternatively decide that that's
> a code bug and make ALTER DOMAIN take it, but I don't think it's worth
> any effort (and this behavior may actually have been intentional, too).
> I think we should just add
>
> where domain_constraint is:
>
> [ CONSTRAINT constraint_name ]
> { NOT NULL | CHECK (expression) }
>
> to the ALTER DOMAIN page, and then remove the claim that it's
> identical to CREATE DOMAIN.
There was some discussion about these issues (ALTER DOMAIN vs CREATE
DOMAIN reference page, as well as the NOT NULL constraint syntax) in and
around
<https://www.postgresql.org/message-id/a4a344ea-9e79-4c42-a9af-899f85bd753b@eisentraut.org;.
All that ended up dying because the NOT NULL constraints feature was
reverted. But there were some subtle details about why the syntax is
the way it is and/or whether that's really intentional and how to
document it. Might be worth reviewing again.
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Cc: peter@eisentraut.org, tgl@sss.pgh.pa.us, david.g.johnston@gmail.com, elionescu@yahoo.com, pgsql-docs@lists.postgresql.org
Subject: Re: incorrect (incomplete) description for "alter domain"
In-Reply-To: <beafea49-f28d-4953-90fe-bf759161ef9d@eisentraut.org>
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