Re: Database design, Keys and some other things

From: JOG <>
Date: 29 Sep 2005 14:33:40 -0700
Message-ID: <>

Okay fair enough. The issue clearly has baggage. But I have used, advocated, and taught the RM for over a decade now, and I am not just trying to be contrary. But I'm not doing down the RM - the primary attraction of RM os that it was not created in an ad-hoc fashion, but rather based on fundamental principles. All my posts were intended to be, were a discussion of a different possible principle to base a mathematical model upon.

I am putting forward for discussion that Codd's Information Principle (based on an Liebniz/essentialist viewpoint that an entity is defined by its attributes, and is nothing more and nothing less than the aggregate of them, [Celko - D&DB]) is not a complete model of the nature of information. Rather I am proposing that there is no single attribute of an entity that can be gauranteed to act as a permenant immutable reference for it (nominalism - there are no universals), and so an external one to represent our concept of an entity be provided.

Difficulties arising from the IP:
Primary Key non-mutability - often necessary to employ internal surrogates that require management [Codd - RM/T paper]. Lack of Internal Referencing checks - often necessary to explicitly use cascade mechanisms to prevent dangling references, orphan records.

Possible Solution:
provide any encoded proposition with an automated reference that guarantees primary key mutability, but is externalised from the data, which then remains a pure encoding of the representation of real-world attributes (essentially the partial map that is the tuple becomes a datatype) [W, Kent - D&R]. Joins may be pivoted on this reference, and integrity is continually maintained by the DBMS between these references to prevent orphan tuples.

Now I'm afraid, I have no more than that to offer at the moment. And obviously its all up for assassination, and thats no problem, shoot. That's why i'm posting - to get your educated opinions. Just don't tell me this sort of discussion isn't valid here (where else?), that I don't roll my sleeves up and do real work or that the questioning the philosophy of axioms is for high school. Received on Thu Sep 29 2005 - 23:33:40 CEST

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