No i don't thing so. The OID can be use tu improve some sql statement, but it
can't be use as primary key. Because it can be change.
I thing the best way is create a new type for some ref key. This type have a
integer as primary key and a OID of joint's objects. The triger need tu update
automaticaly the OID of ref key.
Best regards,
Ngoc-Khoi TO.