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

Alvaro Herrera <alvherre(at)commandprompt(dot)com> writes:
> So, question: do we need pg_constraint rows to exist for all NOT NULL
> constraints, including those in system catalogs, and including those in
> bootstrap catalogs? If we're going to require that, we're going to need
> to add a few initial data lines to the pg_constraint catalog definition,
> plus some code to handle the other bootstrap cases (non bootstrap
> relations).

Installing such rows during bootstrap would be problematic, because what
do you do for catalogs that are created before pg_constraint?

Possible solution is to leave bootstrap's behavior alone, and have a
step during initdb's post-bootstrap stuff that creates a matching
pg_constraint row for every pg_attribute entry that's marked attnotnull.

> We could also declare that we don't need pg_constraint rows for NOT NULL
> constraints in system catalogs; but if we're going to do that, I guess
> we'd better disallow tables from inheriting system catalogs.

I have a feeling that omitting these entries for system catalogs would
bite us in other ways down the road, even if inheritance were the only
soft spot right now.

regards, tom lane