Oracle® DBA Guide to Data Warehousing and Star Schemas

Modeling Star Schemas

In dimensional modeling, there are generally only two kinds of tables:

• Dimensions— Relatively small, denormalized lookup tables containing business descriptive columns that end-users reference to define their restriction criteria for ad-hoc business intelligence queries.

• Facts— Extremely large tables whose primary keys are formed from the concatenation of all the columns that are foreign keys referencing related dimension tables. Facts also possess numerically additive, non-key columns utilized to satisfy calculations required by end-user ad-hoc business intelligence queries.

A simple example of a dimensional data model is shown in Figure 4-1.

Figure 4-1. Example Dimensional Entity Relationship Model

Figure 4-1 represents ...