The Data Warehouse Toolkit: The Definitive Guide to Dimensional Modeling, 3rd Edition

Chapter 11

Telecommunications

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 ...