Free Trial

Safari Books Online is a digital library providing on-demand subscription access to thousands of learning resources.

Share this Page URL

CHAPTER 16: What are logical data models? > Normalization Explained - Pg. 339

CHAPTER 16: What are logical data models? 339 · · averaging. The reason the dimensional model should be limited to numbers is because its design allows for easy navigation up and down hierarchy levels. When traversing hierarchy levels, measures may need to be recalculated for the hierarchy level. For example, a Gross Sales Value Amount of $5 on a particular date might be $100 for the month in which that date belongs. Lines. The relationship lines on a dimensional model represent navigation paths instead of business rules, as in a relational model. Let creativity drive your dimensional structures. The relationships in a dimensional hierarchy do not have to mimic their relational counterparts. You should build dimensions to meet the way the business users think. Scope. The scope of a dimensional model is a collection of related measures that together address a business concern, whereas in a relational model, the scope may be a broad business process, such as order processing or account management. For example, the metrics Number of Product Complaints and Number of Product Inquiries can be used to gauge product satisfaction. Normalization Explained When I turned 12, I received a trunk full of baseball cards as a birthday present from my parents. I was delighted, not just because there may have been a Hank Aaron or Pete Rose buried somewhere in that trunk, but because I loved to organize the cards. I categorized each