So What Exactly is an OID?
An OID is an opaque structure guaranteed unique
in the ORACLE8 universe. It allows up to 2 raised to the power of
128 objects to be identified
(340,283,266,920,938,463,463,374,607,431,768,211,456 objects). An
OID is stored as a 128 bit base 64 value. It is the equivalent of a
pointer used inside the database. Relationships called associations
use the OID to establish connections between objects. These
associations are accomplished using REF calls. There are no
automatic associations as are available for relational tables via
the constraint and referential integrity, all REF type associations
have to be manually coded using either triggers or the new kid on
the block, methods.