Re: question on update/delete rules on views

create rule view_a_r_update as on update to view_a   do instead       update a set two = new.two;

The problem is that your INSTEAD UPDATE rule is not constrained in any
way; it DOES hit every row.  Instead, do something like:
  create rule view_a_r_update as on update to view_a   do instead       update a set two = new.two       where id =
old.id;

where id is a primary key in your table.

Cheers,
Brook