
84 CHAPTER 5 Selecting Materialized Views
three queries. Sometimes, less is more. There is a small drawback, the user queries now
take 7 seconds of disk I/O. If this is not acceptable in rare cases, then another possibility
is to create the Profit_Fact table first and then create the other materialized views from
the Profit_Fact table rather than from the base tables directly. Since the Profit_Fact table
is much smaller than the base tables, the creation time for the other materialized views
can be greatly reduced. We leave the I/O time calculations as an exercise.
5.3 Exploiting Grouping and Generalization
The health of the company depends on monitoring ...