Re: Database design

Marshall Spight wrote:
> JOG wrote:
> >
> > This whole 'flat' debate is nonsense too. Write a database down in its
> > mathematical form, devoid of tables, and tell me how on earth it can be
> > flat (which semantically means two-dimensional of course), deep, fat,
> > thin, whatever. If you mean it doesn't support composite types say
> > that. If you mean it contains no explicit links, say that. Calling it
> > flat is semantically redundant and doesn't aid any real discussion.
>
> Yes, exactly.
>
> Since we are discussing mathematical constructs, we need to
> define our terms first. So what does "flat" mean exactly?
> The term is suggestive merely; there is no formal meaning
> that I am aware of. Mathworld didn't supply any definitions
> outside of the usual topological ones.
>
> Some possibilities:
>
> Relations are flat because all the air went out of them
> after they rolled over some glass.
>
> The candidate proposed a flat tax, meaning that all
> taxes would be expressed in first normal form.
>
> Relations look flat next to Pamela Anderson, but then,
> *any* mathematical structure would.

Any *natural* structure would.

I suspect you do know what someone means when they call relations "flat" but just in case you really don't... As someone who has often brought people to the mathematical definition of dimension related to relations, I think I know what folks usually mean when they call a relation flat. As I posted earlier, you can think of accessing any value in a relation using a row and column or, programmatically, a 2D Array with [i][j].

So, hopefully you can see how a programmer might use the term "dimension" as in the "2D" of the previous sentence, and you have surely heard 2D objects in space referred to as flat (even those with very small 3rd dimensions, such as paper).

So, this doesn't seem to be a mystery, nor an error, but a difference in terminology that should be easy to clear up. I suspect that those with the mathematical definition of dimension related to a relation (which is where I come from) can easily comprehend this other use of the term dimension and related meaning of "flat." Right? --dawn Received on Wed Feb 22 2006 - 14:23:15 CET