The data that are modeled are the data that sit at the heart of the business of the
company. The data model is shaped around whatever is at the core of the business of the
organization.

Granular Data Only

The data model is shaped around ONLY the granular detailed data of the organization.
Bad things happen when the data modeler allows summarized or aggregated data to enter
the data model. When summarized or aggregated, data are allowed to enter the data
model:

• There is a HUGE amount of data to be modeled.


• The formula for calculating the summarized data changes faster than the modeler can create and change
  the model.


• Different people have different formulas for the same or similar calculations.

The first step in building the data model is to remove all derived data—summarized or
aggregated data—from the data model.

Fig. 7.3.1 shows that detailed granular data are separated from summarized or aggregated
data when building the data model.

Chapter 7.3: Data Modeling for the Structured Environment