Re: cataloguing NOT NULL constraints

From: Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
To: Kevin Grittner <kevin(dot)grittner(at)wicourts(dot)gov>
Cc: Alvaro Herrera <alvherre(at)commandprompt(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: cataloguing NOT NULL constraints
Date: 2012-08-16 14:35:45
Message-ID: 1345127470-sup-2641@alvh.no-ip.org
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Excerpts from Kevin Grittner's message of jue ago 02 10:48:02 -0400 2012:
>
> "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov> wrote:
>
> > Don't forget the peculiarities of columns with record types.
>
> I forgot to include the type creation in the example:
>
> test=# create type a as (a1 int, a2 int);
> CREATE TYPE

Thanks for the example. After playing with this, I think that a NOT
NULL constraint attached to a column with a composite type is equivalent
to a CHECK (col IS DISTINCT FROM NULL); at least they seem to behave
identically. Is that what you would expect?

This seems a bit complicated to handle with the way I'm doing things
today; at parse analysis time, when my current code is creating the
check constraint, we don't know anything about the type of the column
IIRC. Maybe I will have to delay creating the constraint until
execution.

--
Álvaro Herrera http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services

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