Kinds of Data Models: Toward a Common Vocabulary

David C. Hay Essential Strategies International

Data Architects are fond of criticizing clients for not properly handling language. Throughout the enterprise the same word is used to mean different things. Different words are used to mean (approximately!) the same thing. An important part of any data governance project is to help the client come to terms with the way it uses language.

But what about us in the data management profession? If a company advertises for a “data modeler”, what exactly is it expecting? For that matter, if you answer the ad, what are you prepared to do?

How do you define a “conceptual model”? What about a “logical model”? “Physical model”? Would your neighbor agree on any of these? But of course, that’s not all. We have to deal also with “entity relationship model”, “object role modeling”, “the semantic web”, and “XML Schema”, among others. Oh, and can anyone define “canonical model”?
It turns out that the data industry is beginning to converge on these and related terms. But it’s not quite done yet. This presentation is a humble attempt to complete the process.

Based on the industry’s history, his proficiency in language and semantics, and, OK, some personal prejudice, David Hay will present (at least his version of) a definitive vocabulary for our field. This will cover not only the traditional terms “Conceptual”, ‘Logical”, and “Physical” models, but introduce two new ones, just to make things interesting: “Semantic” and “Essential” models.

In each case, the term will be coherently defined, along with examples of the techniques appropriate for each.
A moderate amount of audience participation is welcome—as long as the objective is to refine the definitions, not simply to disagree with them.


A veteran of the Information Industry since the days of punched cards, paper tape, and teletype machines, Dave Hay has been producing data models to support strategic information planning and requirements analysis for over thirty years. He has worked in a variety of industries, including, among others, power generation, clinical pharmaceutical research, oil refining, banking, and broadcast. He is President of Essential Strategies International, a consulting firm dedicated to helping clients define corporate information architecture, identify requirements, and plan strategies for the implementation of new systems.
Mr. Hay is the author of the book, Data Model Patterns: Conventions of Thought, Requirements Analysis: From Business Views to Architecture, and Data Model Patterns: A Metadata Map.
Most recently, he wrote Enterprise Model Patterns: Describing the World, and UML and Data Modeling: A Reconciliation, both published by Technics Publications.
Mr. Hay has spoken numerous times to “The Data Modeling Zone”, annual DAMA International Conferences (both in the United States and overseas), annual conferences for various Oracle user groups, and numerous local chapters of both data administration and database management system groups.
He may be reached at dch@essentialstrategies.com or (713) 464-8316. Many of his works can be found at http://articles.essentialstrategies.com.

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