Re: NOT NULL constraints in foreign tables

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@2ndquadrant.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/
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