OIDs

I have a couple of questions about OIDs....

First, why would one choose to not use an OID as the
primary-key/foreign-key-reference for a table? It is unique (good thing) and
lacks business meaning (another good thing), so it seems to me to be just
the thing, a nice surrogate key. Is it just because of the name? I would
agree that as a foreign key reference a la:

create table employee_child (
parent oid references employee(oid),
name varchar(4) ....

looks kind of bad, but that is the worst drawback my
non-postgresql-experienced brain can conjure up.

Second, what is the scale of an OID? Does it map to an INT4 or an INT8? I
will be accessing the data via JDBC so I need to know what java type to use.

Third, is there any bottleneck or other problem associated with using OIDs
versus turning them off and using a self-defined SERIAL field? Or is the
opposite true?

Thanks!
John

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john guthrie
american institutes for research
jguthrie(at)air(dot)org
202-298-2716