Re: ADD CHECK fails for parent table if column used in CHECK is fully-qualified

Manuel Rigger <rigger(dot)manuel(at)gmail(dot)com> writes:
> Consider the following case:

> CREATE TABLE t0(c0 boolean);
> CREATE TABLE t1(c0 boolean) INHERITS(t0);
> ALTER TABLE t0 ADD CHECK(t0.c0);
> -- unexpected: ERROR: missing FROM-clause entry for table "t0"

> Is it expected that this fails?

I don't really have a problem with that. You specified that the
check was on t0, and that would be an invalid constraint for t1.

Now it is a bit weird that you can do this:

regression=# CREATE TABLE t0(c0 boolean);
CREATE TABLE
regression=# ALTER TABLE t0 ADD CHECK(t0.c0);
ALTER TABLE
regression=# CREATE TABLE t1() INHERITS(t0);
CREATE TABLE

That happens because after the ALTER, the check constraint is
remembered as just c0:

regression=# \d t0
Table "public.t0"
Column | Type | Collation | Nullable | Default
--------+---------+-----------+----------+---------
c0 | boolean | | |
Check constraints:
"t0_c0_check" CHECK (c0)

and that can be propagated down to t1. So the system has forgotten
a syntactic detail that perhaps it shouldn't have. But I can't
get excited about changing that.

regards, tom lane