Re: A pk is *both* a physical and a logical object.

From: JOG <>
Date: Thu, 26 Jul 2007 08:06:29 -0700
Message-ID: <>

On Jul 26, 1:47 pm, "David Cressey" <> wrote:
> "JOG" <> wrote in message
> > Just as another example of what i'm on about with this construct
> > m'larkey: Imagine the library has two copies of "harry potter and the
> > deathly hallows". Are they the same book?
> This sounds like "the cat food problem" to me. Is it?

Well I think the cat-food problem was specifically about duplicate propositions, but yes some of the mistakes in its argumentation are related. Not understanding that cans may be recorded individually /or/ as a whole (depending on what a situation requires) could well be another symptom of not thinking in terms of "constructs". I think it also might have a lot of other consequences, reaching from why hidden OID's are a mistake (we need to be able to identify constructs outside in the real world), right through to philosopophical mumbo-jumbo like why the "theseus ship paradox" isn't a paradox at all (where different people just applying different constructs as in the book example).

I certainly think good db admins often recognize all these things by intuition, and experience in designing databases and thats who i've picked it up from - but (to my knowledge) it has never been formalized at the conceptual level. Oh, and apologies for the wanton use of the word "construct". I just don't have a better term. Received on Thu Jul 26 2007 - 17:06:29 CEST

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