Peter Eisentraut <pe...@eisentraut.org> writes:
> But I see that table constraints do not work that way. A command like
> ALTER TABLE t1 ADD NOT NULL c1 does nothing if the column already has a
> NOT NULL constraint. I'm not sure this is correct. At least it's not
> documented. We should probably make the domains feature work the same
> way, but I would like to understand why it works that way first.
That's probably a hangover from when the underlying state was just
a boolean (attnotnull). Still, I'm a little hesitant to change the
behavior. I do agree that named constraints need to "stack", so
that you'd have to remove each one before not-nullness stops being
enforced. Less sure about unnamed properties.
regards, tom lane
