5NF and Database Design
Summary
This article critiques the traditional presentation of fifth normal form (5NF) in relational database theory and argues that it is often unnecessary for practical database design. It shows that starting from business requirements and a complete logical model, you can derive a clean, normalized physical schema using two design patterns: AB-BC-AC triangle and ABC+D star pattern. It also discusses when to use synthetic primary keys versus composite primary keys, explains how to model links with junction tables, and emphasizes avoiding artificial 5NF decomposition in real projects.