# Re: Oracle and PICK

From: Anthony W. Youngman <wol_at_thewolery.demon.co.uk>
Date: Sat, 24 Apr 2004 12:49:50 +0100
Message-ID: <GP3GIoFeRliAFwbx_at_thewolery.demon.co.uk>

In message <PsadnVC91J-hxxzdRVn-hA_at_comcast.com>, Laconic2 <laconic2_at_comcast.net> writes
>The point is, IMO, that you can project a three dimensional relation (or,
>maybe a third order relation) onto a two dimensional space (rows, columns)
>without loss.
>
>If it weren't for the capacity of two dimensional tables to capture and
>retrieve data that might be three dimensional or beyond, a star schema
>would be impossible.
>
>In other words, the table has only two dimensions, but the relation is of
>order 3, and therefore can list a (finite) set of points in a three
>dimensional space.
>
>Mathematical relations are not limited to finite cardinality, but I'm
>putting that limitation on the relations in the relational data model. Now
>that I think of it, is this a legitimate limitiation or not? Your
>thoughts.

Rephrase that. "Is it a *necessary* limitation?". If you don't *need* to apply the restriction, then your solution space is a subset of the available solution space and must, by definition, be incomplete.

You'll probably rephrase me again :-) but to rephrase myself in physics terms - "are you applying a cosmological constant?" - a cosmological constant being "some number we can't explain that just happens to be the fudge factor we need to make things add up".

Think of the recent proof of Fermat's Last Theorem. The proof was all the more elegant because it didn't even prove Fermat directly - the guy just said "oh, if you pick this particular case, it just happens to be Fermat's Theorem". Actually, I'm not at all sure I've picked up your primary point - you were talking about "finite" cardinality and I've picked up on "two-dimensional projection". But my comments about "legitimate" and "necessary" still stand ...
>
>Clear as mud?
>

Probably :-)

Cheers,
Wol

```--
Anthony W. Youngman - wol at thewolery dot demon dot co dot uk
HEX wondered how much he should tell the Wizards. He felt it would not be a
good idea to burden them with too much input. Hex always thought of his reports
as Lies-to-People.
The Science of Discworld : (c) Terry Pratchett 1999
```
Received on Sat Apr 24 2004 - 13:49:50 CEST

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