Stage 6 : Temporal calculation
The Best Foot Forward needs now to define actions to undertake in the future. The previous examples are not sufficient, we need to analyze the evolution of already filed data, and if possible to anticipate their evolution in the future.
OLAP databases are very powerful for that, they provide functions allowing to manipulate temporal inquiries. For example, we could know what week corresponds to 12 June 2000, how much days are between 06 May 1998 and 15 June 2002, or if 29 February 2000 exists or no.
Some engines provide standard datatypes for time dimensions. These dimensions are then characterized by their periodicity (day, week, semester, . ..) and functions exist to convert a periodicity to another. The OLAP engine include all the calendar specifications, and developers no longer worry about complex algorithms, building and maintaining temporal hierarchies.
With small and simple programs, we can now define formulas replying to questions like this:
With relationnal databases, such questions will require very expensive programs, perhaps never giving a response to the user...