Discussion about inheritance

Hello,

I'm using inheritance in my DB with PostgreSQL 7.3.4, and a friend of my
told me that there is a bug in that type of table.

To resume, the problem is:
- a table A have a primary key
- a table B references the primary key of A
- a table C inherits the A fields
- when I insert a tuple in table B that references something inserted at
A, everything is OK.
- when I insert a tuple in table B that references something inserted at
C, a integrity violation occurs.

To me, this looks not like a bug, because the tuple is not at A phisically.

Taking the example of a VIEW: its not possible to reference a column in a
view because the data is not phisically in it.

Here, i put an example where i try to show the "problem" (it is in
portuguese, but I think the names don't seem to be a problem for all):

> PostgreSQL 7.3.4
>
> everton=# create table pessoa (id_pessoa serial NOT NULL PRIMARY KEY,
> nome character varying(30));
>
> everton=# create table pessoafisica(cpf integer) INHERITS(pessoa);
>
> everton=# create table pessoajuridica(cnpj integer) INHERITS(pessoa);
>
> everton=# create table telefone(id_pessoa integer, telefone integer,
> foreign key (id_pessoa) references pessoa (id_pessoa));
>
> everton=# insert into pessoa(nome) values ('Everton');
>
> everton=# insert into pessoafisica(nome, cpf) values ('Alencar', 123);
>
> everton=# insert into pessoajuridica(nome, cnpj) values ('Philler', 999);
>
> everton=# select * from pessoafisica;
>   id_pessoa |  nome   | cpf
> -----------+---------+-----
>           3 | Alencar | 123
>
> everton=# select * from pessoajuridica;
>   id_pessoa |  nome   | cnpj
> -----------+---------+------
>           4 | Philler |  999
>
> everton=# select * from pessoa;
>   id_pessoa |  nome
> -----------+---------
>           2 | Everton
>           3 | Alencar
>           4 | Philler
>
> everton=# insert into telefone(id_pessoa, telefone) values (2, 5410000);
> INSERT 22234 1
> everton=# insert into telefone(id_pessoa, telefone) values (4, 5413443);

> ERROR:  $1 referential integrity violation - key referenced from
> telefone not found in pessoa
>

Like I said, this is not a problem for me, but I want to know if someone
thinks this can be considered a real problem, or if something will be done
to try to correct (or modify) this operation.

Thanks to all,

Marcelo Soares
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