Book Image

Learning Apache Cassandra - Second Edition

Book Image

Learning Apache Cassandra - Second Edition

Overview of this book

Cassandra is a distributed database that stands out thanks to its robust feature set and intuitive interface, while providing high availability and scalability of a distributed data store. This book will introduce you to the rich feature set offered by Cassandra, and empower you to create and manage a highly scalable, performant and fault-tolerant database layer. The book starts by explaining the new features implemented in Cassandra 3.x and get you set up with Cassandra. Then you’ll walk through data modeling in Cassandra and the rich feature set available to design a flexible schema. Next you’ll learn to create tables with composite partition keys, collections and user-defined types and get to know different methods to avoid denormalization of data. You will then proceed to create user-defined functions and aggregates in Cassandra. Then, you will set up a multi node cluster and see how the dynamics of Cassandra change with it. Finally, you will implement some application-level optimizations using a Java client. By the end of this book, you'll be fully equipped to build powerful, scalable Cassandra database layers for your applications.
Table of Contents (14 chapters)

Compound keys represent parent-child relationships


In the What is Cassandra and why Cassandra? section of Chapter 1, Getting Up and Running with Cassandra, you learned that Cassandra is not a relational database despite some surface similarities. Specifically, this means that Cassandra does not have a built-in concept of the relationships between data in different tables. There are no foreign key constraints and there's no JOIN clause available in the SELECT statements; in fact, there is no way to read from multiple tables in the same query whereas relational databases are designed to explicitly account for the relationships between data in different tables, whether they're one-to-one, one-to-many, or many-to-many. Cassandra has no built-in mechanism for describing or traversing inter-table relationships.

That being said, Cassandra's compound primary key structure provides an ample affordance for a particular kind of relationship—the parent-child relationship. This is a specific type of one...