The requirements definition completely drives the data design for the data warehouse. Data design consists of putting together the data structures. A group of data elements form a data structure. Logical data design includes determination of the various data elements that are needed and combination of the data elements into structures of data. Logical data design also includes establishing the relationships among the data structures.
Let us look at Figure 10-1. Notice how the phases start with requirements gathering. The results of the requirements gathering phase is documented in detail in the requirements definition document. An essential component of this document is the set of information package diagrams. Remember that these are information matrices showing the metrics, business dimensions, and the hierarchies within individual business dimensions.
The information package diagrams form the basis for the logical data design for the data warehouse. The data design process results in a dimensional data model.
Before we proceed with designing the dimensional data model, let us quickly review some of the design decisions you have to make:
Choosing the process.
Selecting the subjects from the information packages for the first set of logical structures to be designed. ...