what about uniqueness of inherited primary keys

Hello list,

what about uniqueness of inherited primary keys ?

eg you have :

create table objects (
  id int4,
  date_created   timestamp(0),
  primary key (id)
);

create table persons (
  firstname  varchar(100),
  lastname  varchar(100)
) inherits (objects);

now ...

insert into objects (id) values (1);
A repetition of this line would cause an unique-constraint error of
objects_pkey.

insert into persons (id, firstname, lastname) values (1, 'Super', 'Man');
insert into persons (id, firstname, lastname) values (1, 'Bat', 'Man');
works though it violates the inherited constraint.

A  select * from objects;  shows id=1 three times.

delete * from objects;   empties both tables.

after   ALTER TABLE public.persons  ADD CONSTRAINT persons_pkey PRIMARY
KEY(id);
I can still insert at least one record with id=1 in each table.

select count(*) from objects where id=1;
results  2

Shouldn't we expect to have unique entries in a primary key collumn ?