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)

A table for status updates


In the MyStatus application, we'll begin by creating a timeline of status updates for each user. Users can view their friends' status updates by accessing the timeline of the friend in question.

The user timeline requires a new level of organization, which we didn't see in the users table that we created in the previous chapter. Specifically, we have two requirements:

  • Rows (individual status updates) should be logically grouped by a certain property (the user who created the update)
  • Rows should be accessible in a sorted order (in this case, by creation date)

Fortunately, compound primary keys provide exactly these qualities.

Creating a table with a compound primary key

The syntax for creating tables with compound primary keys is a bit different from the single-column primary key syntax we saw in the previous chapter. We create a user_status_updates table with a compound primary key, as follows:

CREATE TABLE "user_status_updates" ( 
  "username" text, 
  "id" timeuuid...