Inheritance: Performance & Indexes

Just curious:
 create table a (x int4 primary key); create table a1 () inherits (a);
 [...]
 delete from a where x = 1000;

I take it that this is equivalent to:
 delete from only a where x = 1000; delete from only a1 where x = 1000;

In particular, for performance reasons I should try to limit the
delete to a1 wherever possible?

Also, it looks like a1 doesn't inherit the primary key index.  Is that
intentional or a bug?

Finally, is it possible to specify that x values be unique across
both a *and* a1, without triggers?

-- 
Itai Zukerman  <http://www.math-hat.com/~zukerman/>