Ad Hoc Queries and Enterprise Discovery
“Usage Considerations: Simple and Complex Queries” on page 41 established that discovery is the critical focus of data warehousing, not simple reporting. The trends fueling the data warehousing revolution are based on the need for information that can be acted upon proactively. Report-oriented systems rely on predefined questions that produce reports of what has already happened. This type of information can only produce evidence that a situation that has already occurred must be reacted to.
A data warehouse must have the capability of performing high performance, complex, ad hoc queries if it is to capitalize on the advantages of warehousing its business data. Furthermore, that data must be available for analysis in detail, as well as summary, formats. The value of data warehousing comes from being able to ask unplanned questions on detail data.