Design the Dimensional Model
As outlined in Chapter 3: Retail Sales, there are four key decisions made during the design of a dimensional model:
- Identify the business process.
- Declare the grain of the business process.
- Identify the dimensions.
- Identify the facts.
The first step of identifying the business process is typically determined at the conclusion of the requirements gathering. The prioritization activity described in Chapter 17 establishes which bus matrix row (and hence business process) will be modeled. With that grounding, the team can proceed with the design tasks.
The modeling effort typically works through the following sequence of tasks and deliverables, as illustrated in Figure 18-1:
- High-level model defining the model’s scope and granularity
- Detailed design with table-by-table attributes and metrics
- Review and validation with IT and business representatives
- Finalization of the design documentation
As with any data modeling effort, dimensional modeling is an...