This chapter unfolds a bit differently than preceding chapters. We begin with a case study overview but we won't be designing a dimensional model from scratch this time. Instead, we'll step into a project midstream to conduct a design review, looking for opportunities to improve the initial draft schema. The bulk of this chapter focuses on identifying design flaws in dimensional models.
We'll use a billing vignette drawn from the telecommunications industry as the basis for the case study; it shares similar characteristics with the billing data generated by a utilities company. At the end of this chapter we'll describe the handling of geographic location information in the data warehouse.
Chapter 11 discusses the following concepts:
- Bus matrix snippet for telecommunications company
- Design review exercise
- Checklist of common design mistakes
- Recommended tactics when conducting design reviews
- Retrofitting existing data structures
- Abstract geographic location dimensions
Telecommunications Case Study and Bus Matrix
Given your extensive experience in dimensional modeling (10 chapters so far), you've recently been recruited to a new position as a dimensional modeler on the DW/BI team for a large wireless telecommunications company. On your first day, after a few hours of human resources paperwork and orientation, you're ready to get to work.
The DW/BI team is anxious for you to review its initial dimensional design. So far it seems the project is off to ...