Re: Re: starting to review the Extend NOT NULL representation to pg_constraint patch

Excerpts from Robert Haas's message of lun jun 27 10:35:59 -0400 2011:
> On Mon, Jun 27, 2011 at 3:08 AM, Dean Rasheed <dean(dot)a(dot)rasheed(at)gmail(dot)com> wrote:

> > I would summarise the consistency requirements as:
> >
> > 1). ADD CONSTRAINT should leave both parent and child tables in the
> > same state as they would have been if the constraint had been defined
> > at table creation time.
> >
> > 2). DROP CONSTRAINT should leave both parent and child tables in the
> > same state as if the constraint had never existed (completely
> > reversing the effects of ADD CONSTRAINT).
> >
> > I don't have a strong opinion as to whether or not the NOT NULL part
> > of a PK should be inherited, provided that it is consistent with the
> > above.
> >
> > I guess that if I were forced to choose, I would say that the NOT NULL
> > part of a PK should not be inherited, since I do think of it as part
> > of the PK, and PKs are not inherited.
>
> OK, I see your point, and I agree with you.

Interesting. This whole thing requires quite a bit of rejiggering in
the initial transformation phase, I think, but yeah, I see the points
here and I will see to them. Does this mean that "NOT NULL PRIMARY KEY"
now behaves differently? I think it does , because if you drop the PK
then the field needs to continue being not null.

And here I was thinking that this was just a quick job to enable NOT
VALID constraints ...

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Álvaro Herrera <alvherre(at)commandprompt(dot)com>
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