From: | Chris Bitmead <chrisb(at)nimrod(dot)itg(dot)telstra(dot)com(dot)au> |
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To: | "Robert B(dot) Easter" <reaster(at)comptechnews(dot)com> |
Cc: | Zeugswetter Andreas SB <ZeugswetterA(at)wien(dot)spardat(dot)at>, "'Postgres Hackers List'" <hackers(at)postgresql(dot)org> |
Subject: | Re: AW: Postgresql OO Patch |
Date: | 2000-05-24 23:45:59 |
Message-ID: | 392C69B7.63A4BCEF@nimrod.itg.telecom.com.au |
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Lists: | pgsql-hackers |
"Robert B. Easter" wrote:
> > Imho this alone more than justifies the patch.
> > We should also change our keyword "inherits" to "under".
> >
>
> I don't agree. UNDER only provides for single inheritance according to spec.
> Making it multiple inherit would break UNDER's basic idea of enabling hierarchy
> trees that contain subtables under a single maximal supertable.
I don't see that it's a "basic idea". I see it as crippled subset of
SQL3-94.
> is ok too. But the meaning is different than above. It creates an independent
> child table that is not contained under either parent so that the parents can
> be dropped.
I wouldn't like to define an object model in terms of what happens when
the meta-data is modified.
> You use UNDER when the child/subtabe to share the exact same
> physical PRIMARY KEY of the SUPERTABLE. In inherit, the child inherits a
> composite key from the parents, but that key is new physically, not the same
> physically as any parents.
Issues like primary keys are the sort of stuff that probably kept the
committee arguing long enough they were too lazy to come to a decision.
Myself, I'm not too interested in primary keys since they are not a very
OO idea anyway.
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