Re: Functional dependencies and GROUP BY

From: Peter Eisentraut <peter_e(at)gmx(dot)net>
To: Alex Hunsaker <badalex(at)gmail(dot)com>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: Functional dependencies and GROUP BY
Date: 2010-07-17 10:15:18
Message-ID: 1279361718.17928.1.camel@vanquo.pezone.net
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On fre, 2010-07-16 at 22:29 -0600, Alex Hunsaker wrote:
> The only corner case I have run into is creating a view with what I
> would call an implicit 'not null' constraint. Demonstration below:
>
> create table nn (a int4 not null, b int4, unique (a));
> select * from nn group by a; -- should this work? I think not?

I believe I referred to this upsthread. There is another patch in the
commitfest about explicitly representing NOT NULL constraints in
pg_constraint. Then this case would create a dependency on those
constraints. So we need to get that other patch in first.

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