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 primary keys in column families


Now that we've established the relatively familiar-looking column family structure of users-a table with a simple primary key-let's move on to a table with a compound primary key. To start, let's take a look at home_status_updates, a fairly straightforward table. Recall that this table has a partition key timeline_username; a clustering column status_update_id; and two data columns, body and status_update_username column.

We'll use the LIST command to take a look at the contents of the column family and, beforehand, we'll use the ASSUME command to set the value output format to utf8. This has a similar effect as the AS modifier we used earlier, but it applies to all cells in a column family, rather than only cells with a specific name:

ASSUME home_status_updates VALIDATOR AS utf8; 
LIST home_status_updates;

The output of the LIST command takes the same general shape as that for the users column family, but the way the information is arranged might come...