Re: Can't find not null constraint, but \d+ shows that

On Wed, Apr 10, 2024 at 7:01 PM Alvaro Herrera <alvherre@alvh.no-ip.org> wrote:
>
> On 2024-Apr-10, jian he wrote:
>
> > another related bug, in master.
> >
> > drop table if exists notnull_tbl1;
> > CREATE TABLE notnull_tbl1 (c0 int not null, c1 int);
> > ALTER TABLE notnull_tbl1 ADD CONSTRAINT Q PRIMARY KEY(c0, c1);
> > \d+ notnull_tbl1
> > ALTER TABLE notnull_tbl1 ALTER c0 DROP NOT NULL;
> > ALTER TABLE notnull_tbl1 ALTER c1 DROP NOT NULL;
> >
> > "ALTER TABLE notnull_tbl1 ALTER c0 DROP NOT NULL;"
> > should fail?
>
> No, this should not fail, and it is working correctly in master.  You
> can drop the not-null constraint, but the column will still be
> non-nullable, because the primary key still exists.  If you drop the
> primary key later, then the column becomes nullable.  This is by design.
>

now I got it. the second time, it will fail.
it should be the expected behavior.

per commit:
https://git.postgresql.org/cgit/postgresql.git/commit/?id=14dd0f27d7cd56ffae9ecdbe324965073d01a9ff
In the function dropconstraint_internal, I changed "foreach" to
"foreach_int" in some places,
and other minor cosmetic changes within the function
dropconstraint_internal only.

Since I saw your changes in dropconstraint_internal, I posted here.
I will review your latest patch later.