[BOOK REVIEW] The Data Warehouse Toolkit by Ralph Kimball/Dimensional Modeling

#3 Book: The Data Warehouse Toolkit, 3rd edition from class Data Engineer by Tuan Anh Pham

Brief introduction

Dimensional modeling is a longstanding technique for making databases simple.

Simplicity is the key element for database design, which can be achieved with dimensional modeling technique.

A data model that starts simple has a chance of remaining simple at the end of the design.

While a dimensional model contains the same information as a third normal form (3NF) model, in fact they are quite different from each other. The key difference lies in the level of normalization. Both consist of joined relational tables. However, 3NF models prefer distributing information according to these normal forms respectively 1NF, 2NF and 3NF into smaller and smaller tables. It makes it way too complicated for data queries, which overwhelms that database optimizers and results in horrible query performance.

A dimensional model contains the same information as a normalized model, but packages the data in a format that delivers user understandability, query performance, and resilience to change.

Fact table

The fact table in a dimensional model stores the performance measurements resulting from an organization’s business process events.