Non-First Normal Forms ( 1NF) and MongoDB: an alternative to 4NF to address 3NF anomalies

SQL databases are grounded in relational algebra, but they are not the only databases with a strong theoretical basis. MongoDB, designed as a document database to solve practical engineering problems and improve developer experience, also builds on theory. It supports non–first-normal-form schemas and extends relational operators to work with them. This foundation is described in a 1986 paper, published 23 years earlier: Theory of Non-First Normal Form Relational Databases MongoDB's aggregation pipeline operators ( $unwind , $group , $lookup , set operations) are concrete implementations of the paper's abstract algebraic operators. I've build the following examples while reading the paper to illustrate the concepts with practical examples. The Basic ¬1NF Data Model The paper defines nested relations where attributes can be atomic or relation-valued: This structure records facts about employees, like some information about their children, their skills, and exams they passed. This maps d