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

Silverston c09.tex V2 - 11/21/2008 3:16am Page 503

Data Warehouse Models 503

an enterprise data model provides a choice of one of the alternatives, thus

providing some standardization without being too rigid because different

applications have different needs. There are times that an application may

choose to implement both of the styles shown in the enterprise data model.

For example, an application may use a level 1 style of modeling for a critical

attribute such as order date and use the level 3 style for the many other

status types of data. This is not the same as advocating you maintain the same

data redundantly in both alternative data model structures, which we do not

recommend at all. You also saw that some structures in the enterprise data

model were consistent and agreed upon across the enterprise as a whole, such

as contact mechanisms. In this case, there may not be a need to show different

alternatives.

The enterprise model needs to be used properly. Think of it as a means to

show generally accepted and standard data model structures, but sometimes

it can also show alternatives. In these cases, data modelers can look at the

enterprise data model and pick the alternative that best meets the needs of

their application.

Data Warehouse Models

Each enterprise has its own unique requirements regarding its decision support

and reporting needs. In general, the decision support environments provide ...