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To: Hannu Krosing <hannu@tm.ee>
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Subject: Re: Thus spoke SQL3 (on OO)
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Hannu Krosing wrote:
> 
> Chris Bitmead wrote:
> >
> > Hannu Krosing wrote:
> >
> > > Chris, what is your position on having a single primary key for all
> > > inherited columns ?
> >
> > What is the significance of a primary key compared to any old unique
> > key?
> 
> I don't know ;) Some theorists seem to think it important, and PG allows
> only one PK per table.
> 
> I just meant that primary key (as well as any other uniqe key) should be
> inherited from parent table

What object theory would say is that oid uniquely identifies an object.
Other unique keys should usually be inherited.