Preface

Among the NoSQL databases, Neo4j is generating a lot of interest due to the following set of features: performance and scalability, robustness, its very natural and expressive graph model, and ACID transactions with rollbacks.

Neo4j is a graph database. Its model is simple and based on nodes and relationships. The model is described as follows:

Before Neo4j introduced Cypher as a preferred query, utilizing Neo4j in a real-world project was difficult compared to a traditional relational database. In particular, querying the database was a nightmare, and executing a complex query required the user to write an object, thereby performing a graph traversal. Roughly speaking, a traversal is an operation that specifies how to traverse a graph and what to do with the nodes and relationships found during the visit. Though it is very powerful, it works in a very procedural way (through callbacks), so its readability is poor and any change to the query means modifying the code and building it.

Cypher, instead, provides a declarative syntax, which is readable and powerful, and a rich set of graph patterns that can be recognized in the graph. Thus, with Cypher, you can write (and read) queries much more easily and be productive from the beginning. This book will guide you through learning this language from the ground up, and each topic will be explained with a real-world example.