Examine the dimensional model (star schema) shown in Figure 32.13. This model describes part of a database that will provide decision support for a taxi company called FastCabs. This company provides a taxi service to clients who can book a taxi either by phone a local office or online through the company’s Web site. The owner of FastCabs wishes to analyze last year’s taxi jobs to gain a better understanding of how to resource the company in the coming years.
(a) Provide examples of the types of analysis that can be undertaken, using the star schema in Figure 32.13.
(b) Provide examples of the types of analysis that cannot be undertaken, using the star schema in Figure 32.13.
(c) Describe the changes that would be necessary to the star schema shown in Figure 32.13 to support the following analysis. (At the same time consider the possible changes that would be necessary to the transaction system providing the data.)
(d) Identify examples of natural and surrogate keys in the star schema shown in Figure 32.13 and describe the benefits associated with using surrogate keys in general.
(e) Using examples taken from the dimensional model of Figure 32.13, describe why the model is referred to as a “star” rather than a “starflake” schema.
(f) Consider the dimensions of Figure 32.13 and identify examples that may suffer from the slowly changing dimension problem. Describe for each example, whether type I, II, or III would be the most useful approach for dealing with the change.