From: JL
To: Editor
Date: 12 Apr 2004
Aargh! From comp.databases.theory, today.
Is it just me, or is 'ontology' just a new buzzword d'annee?
From: "Laconic2"
Newsgroups: comp.databases.theory
Subject: Re: Normalization by Composing, not just Decomposing
Date: 12 Apr 2004
Your original question started me thinking in a new
direction. While others and I would
like to keep the word "normalization" reserved for a relatively
specific concept, there's no reason why we can't start with individual data
values or variables, and compose our way up to schemas.
But first, I want to suggest that you can analyze a body of data
values (which I'll just call "items"), back to entities without
regard to relations as such.
The following are assumptions of mine, although some of them can
be derived from some minimal set of assumptions. You may agree or disagree.
Every (instance of a) data value specifies an attribute.
Every attribute has a domain, which is the set of values that
can specify the attribute.
Every attribute describes either a relationship or an entity.
Every relationship associates two or more entities.
The entities are discovered from the underlying ontology of some
subject matter.
Notice that, in the above, I've said nothing about columns,
rows, tables, schemas, tuples or relations.
Or for that matter about databases, files, lists, or the like. It's just a body of data consisting of
values.
Now we can proceed to the question of composition. We can compose lists, fields, records,
files, columns, rows, and tables. Take
your pick, or go consult the oracle at Delphi.
The question is, when does it make sense to compose data into a
structure, and when does the composition do more harm than good?
From: Fabian Pascal
To: JL
I have maintained for a very long time that as long as there
is no systemic requirement for knowledge, there is every reason to expect
people will wake up one morning and try to reinvent the world, without the
benefit of all that happened before that morning.
This is the situation in the IT industry in particular and,
with some exceptions, in American business and society in general. And it's
getting worse by the day.
Therefore, you should be surprised if you did not encounter
such things.
C. J. Date Comment: Yeah… See Philip A. Bernstein, Synthesizing Third Normal Form
Relations from Functional Dependencies, ACM TODS 1, No. 4 (December
1976), summarized in AN
INTRODUCTION TO DATABASE SYSTEMS, 8th Ed., ref. 12.1, p.
378-9.
Posted
07/09/04
