"Christopher Kings-Lynne" <chriskl@familyhealth.com.au> writes:
> Am I misunderstanding how the mechanism works, or is this a big, not easily
> solved, problem?
The latter. Check the list archives for previous debates about this.
It's not real clear whether an inherited primary key should be expected
to be unique across the whole inheritance tree, or only unique per-table
(IIRC, plausible examples have been advanced for each case). If we want
uniqueness across multiple tables, it'll take considerable work to
create an index mechanism that'd enforce it.
regards, tom lane