From: | Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> |
---|---|
To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
Cc: | Pg Hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: NOT NULL constraints in foreign tables |
Date: | 2012-08-17 20:08:25 |
Message-ID: | 1345233328-sup-9446@alvh.no-ip.org |
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Lists: | pgsql-hackers |
Excerpts from Robert Haas's message of vie ago 17 15:44:29 -0400 2012:
> On Fri, Aug 17, 2012 at 2:58 PM, Alvaro Herrera
> <alvherre(at)2ndquadrant(dot)com> wrote:
> > I mean, what are NOT NULL in foreign tables for? Are they harmed or
> > helped by having pg_constraint rows?
>
> As I've mentioned when this has come up before, I think that
> constraints on foreign tables should be viewed as declarative
> statements about the contents of the foreign data that the DB will
> assume true. This could be useful for a variety of purposes:
> constraint exclusion, query optimization, etc.
So pg_constraint rows for NOT NULLs are a good thing, right?
In general, it seems to me that you're saying we should just lift the
DefineRelation-enforced restriction that foreign tables ought not to
have constraints. So if the user wants to specify
CREATE FOREIGN TABLE people (
who person CHECK (who IS OF TYPE 'human'),
..
) server foobar;
we ought to let them. Correct?
--
Álvaro Herrera http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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