Introducing dimensional modeling
So far, you have dealt with the Jigsaw puzzles' database; a database used for daily operational work. In the real world, a database like this is maintained by an On-Line Transaction Processing (OLTP) system. The users of an OLTP system perform operational tasks; they sell products, process orders, control stock, and so on.
As a counterpart, a data warehouse is a non-operational database; it is a specialized database designed for decision support purposes. Users of a data warehouse analyze the data, and they do it from different points of view.
The most used technique for delivering data to data-warehouse users is dimensional modeling. This technique consists of building a star-like schema with dimension tables surrounding a fact table, making databases simple and understandable.
The primary table in a dimensional model is the fact table. A fact table stores numerical measurements of the business as quantity of products sold, amount represented by the sold...
