Oliver Elphick wrote:
> These are not subclasses but totally unrelated. Suppose you had
>
> parent (id char(2))
> child1 (a int4)
> child2 (a timestamp)
>
> and someone asks for
>
> select sum(a) from parent*
>
> since the types are incompatible, the answer would be nonsense.
That query would be disallowed, for the reason you note. Ambigous
coloumns would need to be specified by class.attribute.
