The Data Model Resource Book, Volume 3: Universal Patterns for Data Modeling

Silverston c03.tex V2 - 11/21/2008 2:59am Page 117

Hybrid Contextual Role Pattern 117

Hybrid Contextual Role Pattern

In this section of the chapter, we look at a hybrid pattern that combines

some characteristics of Level 2 and Level 3 type patterns. In this pattern it

can be shown that a mix of both styles can produce a valid data model that

incorporates the best of both worlds.

Why Do We Need This Pattern?

We have found that a very effective strategy in data modeling is to model

using both a specific and a generalized style of modeling. One may use

a specific style of modeling in order to better understand the information

requirements as well as use a generalized style of modeling in order to serve

as a solid, flexible foundation for the database design. It is possible to use these

different styles of modeling by creating two different models or, as shown

in the following pattern, it is possible to have one model that includes both

the specific as well as a generalized style of modeling. When you have a

model like this, you can show different views of the data model to different

audiences. For example, you may show a view of the specific style of modeling

to business representatives and show the generalized style of modeling to

architects.

Another advantage of this style of modeling is that it provides possible

alternatives that can be chosen at physical database design. The physical

database designer ...