Recent Developments in Database Technology:
Type Inheritance, Temporal Data & the TransRelational Model
by Chris Date
This seminar takes an indepth look at three important new developments in the field of data and database management: business rules, type inheritance, and temporal data. The overall objective in each case is to provide a careful explanation of the foundations of the technology in question; thus, the primary focus throughout is on concepts, principles, and theory, rather than on commercial products.
However, practical implications are discussed wherever appropriate; in particular, features of the SQL standard that might be applicable are explained and analyzed in depth.
More and more, IT professionals (and increasingly, end users as well) are coming to regard "business rules" as a new and better way to build and maintain applications.
Part I of this seminar explains this new technology and analyzes the claims that are made for it, concluding that, for the most part, at least those claims are justified.
The concepts of subtyping and type inheritance have been around for many years (especially in the object world); indeed, languages and products supporting those concepts, in one form or another, have also been available in the marketplace for some considerable time. Yet there is no consensus on any well-defined (i.e., formal, abstract, robust, and rigorous) model of inheritance, with the consequence that those existing languages and products are all ad hoc to a degree, and they all exhibit surprising (and indeed undesiderable) behavior on occasion.
Part II of this seminar presents a model of inheritance that certainly is "formal, abstract, robust, and rigorous" (and not ad hoc).
Thanks to the ever-decreasing cost of storage and the advent of Data Warehouse technology, the idea of maintaining historical data has become not just a goal but a reality for many organizations. As a consequence, the ability to deal properly with the time dimension is becoming increasingly important. Yet today's database management systems offer absolutely nothing to help with this important requirement. Help is on its way, however.
Part III of this seminar describes an approach to the problem that looks set to address the (surprisingly complicated!) issue of proper support for temporal databases.
- Business Rule Technology
- A Relation Perspective
- Twelve Rules for Business Rules
- Inheritance: the basic idea
- Some implications of this idea
- Type inheritance and the SQL standard
- Temporal Database Principles
- Temporal Databases and the SQL standard