CHAPTER 14Derived Schemas
Performance is a guiding principle of dimensional design, as you learned in Chapter 1. It is also one of the foundational principles of data warehousing in general. By restructuring data at load time, rather than query time, answering analytic questions about business processes is faster and easier.
Sometimes, however, faster is not enough. While a well-designed schema can deliver answers to most queries with reasonable rapidity, some queries will require more complex processing. As data sets grow large, even simple queries may exhibit degraded performance.
Luckily, there are solutions to these problems. In this chapter, you will learn how derived tables take information from an existing dimensional schema and restructure ...