Re: Enforce primary key on every table during dev?

We want to enforce a policy, partly just to protect those who might forget, for every table in a particular schema to have a primary key.  This can't be done with event triggers as far as I can see, because it is quite legitimate to do:

BEGIN;

CREATE TABLE foo (id int);

ALTER TABLE foo ADD PRIMARY KEY (id);

COMMIT;

It would be nice to have some kind of "deferrable event trigger" or some way to enforce that no transaction commits which added a table without a primary key.

Any ideas?

Thanks,

Jeremy