Re: BUG #5477: CREATE DOMAIN NOT NULL constraints not always enforced for INSERT with subquery - Mailing list pgsql-bugs

Tom Lane  wrote:

< NOT NULL constraints at the domain level suck. Don't use 'em.

+1

As someone who uses domains very heavily, I can attest that the
semantics of that are very weak.  Whether a domain is nullable
depends almost entirely on the context of its use, which you can't
(and shouldn't try to) anticipate on its declaration.

-Kevin