5 - Some Observations on Data Models and Data Modeling

Abstract

Entity relationship models are limited in what they can express. It helps to be aware of the limitations up front, since they can affect the choices made as to how the enterprise being modeled is represented. It is a very desirable characteristic of data models that they can be developed as models of things that exist in the real world but then be used as models of data records. This chapter describes certain limitations that are there in data modeling. These limitations influence how a particular situation is chosen to be modeled so that one is able to say the things that are most important. One of the key challenges data modelers face is that the characteristics of a good data model depend on the purpose. So something could be appropriate in the context of an application data model, but not in the context of an enterprise or integration data model. The requirements that must be met to manage information include—knowing what information exists and what it is about, extracting portions of the information suitable for a particular purpose, exchanging data between organizations and systems, integrating information from different sources, resolving things they already have information about, and information about new things, sharing the same data between applications and users with different views, and managing the data, including history, for life.