"Kynn Jones" <kynnjo@gmail.com> writes:
> In short, my question is: is there a way to designate a pre-existing
> UNIQUE INDEX (based on data contained in NOT NULL fields) as the basis
> for a table's PRIMARY KEY?
No. If there were, that client software you mention would very likely
still get confused. Both the SQL standard and a lot of code assume
that the constituents of a PRIMARY KEY are just-plain-columns.
regards, tom lane