Chapter 8. Dimensions

In Chapter 7, we described materialized views, which can be used to precompute and store results of frequently used queries. A major benefit of doing this is that you can use query rewrite to transparently rewrite queries to use these materialized views, thus significantly reducing the query response time. One important type of metadata for query rewrite is a database object called a dimension, which allows you to declare relationships in your data warehouse and allows the optimizer to rewrite more queries to use materialized views. In this chapter, we will discuss how to create dimensions as part of the logical design of your data warehouse. In Chapter 9, we will then discuss how these dimensions can be used by query rewrite. ...

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