Re: Review: Non-inheritable check constraints

rhaas=# create table A(ff1 int);
CREATE TABLE
rhaas=# create table B () inherits (A);
CREATE TABLE
rhaas=# create table C () inherits (B);
CREATE TABLE
rhaas=# alter table only b add constraint chk check (ff1 > 0);
ALTER TABLE
rhaas=# alter table a add constraint chk check (ff1 > 0);
NOTICE:  merging constraint "chk" with inherited definition
ALTER TABLE

At this point, you'll find that a has a constraint, and b has a
constraint, but *c does not have a constraint*.  That's bad, because
a's constraint wasn't "only" and should therefore have propagated all
the way down the tree.

Apologies, I did not check this particular scenario.

I guess, here, we should not allow merging of the inherited constraint into an "only" constraint. Because that breaks the semantics for "only" constraints. If this sounds ok, I can whip up a patch for the same.