Re: Pizza Example

From: Eric Kaun <>
Date: Mon, 19 Apr 2004 13:42:22 GMT
Message-ID: <2HQgc.9747$>

"Anthony W. Youngman" <> wrote in message

> In message <
HLyec.53517$>, Eric Kaun
> <> writes
> >> I want my cake and eat it too! The PICK structure does what I have
> >> described and is "amenable to automated deduction" and it seems to me
> >> there is some value in that, but I'm still poking and prodding to
> >> what that might be.
> >
> >Of course it's amenable, just much less so. It's its lack of symmetry and
> >consistency that poses a problem. By nesting values inside values (and
> >a further layer inside that, I believe), you complicate the algebras,
> >closure, and optimizations. Relational is much simpler, hence its power.
> Define "simple".

Good question; in this case I meant simple as advocated by Occam's Razor. Fewer concepts, and more consistent notation.

> So if I run a query, that gives me a view of a complex object, why does
> it give me an indeterminate number of copies of a piece of data that is
> stored just once?

I don't know what you mean here.

> Or, I want to find all the attributes of a single, real-world object.
> With relational, that's a complex query.

Define "complex." It usually depends on the "object" - oh, can you define that as well?

> With Pick, it's "here's the
> (singular) primary key, get the data".

That's certainly possible in SQL too, just as it's possible to be normalized in Pick. However, your statement is just hand-washing, since "the data" is what the entire disagreement is about. Is it a set of attribute values? Is it an object graph? Is it both, meaning we've decided in advance the view of "the object" everyone must have because it's "real world" (can you define that?).

> As I said, define "simple" :-)
> As for saying "it complicates the algebra...", WHY? It makes it easier
> to do stupid things, but it doesn't affect the algebra and, indeed,
> despite making it easier to be stupid, in practice it seems to make it
> less common.

You have separate notation for values, sub-values, sub-sub-values, ... sub^N-values, whatever N is (once I heard 3, once I heard 6).

  • erk
Received on Mon Apr 19 2004 - 15:42:22 CEST

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