Re: Character string relation and functional dependencies

From: Tegiri Nenashi <TegiriNenashi_at_gmail.com>
Date: Thu, 6 Dec 2007 16:24:39 -0800 (PST)
Message-ID: <cd2ad8bd-78ca-433d-bc0f-3e7ef0c0fe2a_at_e6g2000prf.googlegroups.com>


On Dec 6, 2:38 pm, Jonathan Leffler <jleff..._at_earthlink.net> wrote:
> Tegiri Nenashi wrote:
> > On Dec 6, 9:40 am, rp..._at_pcwin518.campus.tue.nl (rpost) wrote:
> >> Another difference is that database tables are finite and variable,
>
> > Oh, relations in database world are certainly not restricted by finite
> > cardinality.
>
> I thought that computers are finite, so the relations containable in
> them are too - even if damn large. There's a big difference between
> very large and infinite.

This doesn't really matter. You can still reason about infinite relations with finite resources available on you computer platform.

> One ultimate limitation is the uniqueness requirement. Suppose you have
> a table with two integer columns. Since the range of the integer types
> are finite (even if your DBMS handles multi-precision integers), then
> the maximum number of distinct rows in the relation is also finite.

All computer algebra systems work with numbers which are not restricted by a whim of hardware architects. 16/32/64 bit integer numbers (let alone floats)? give me a break! Received on Fri Dec 07 2007 - 01:24:39 CET

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