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)

Consistency in action


For a single-node cluster, consistency and replication factor didn't matter since you had only one copy of the data residing on the lone instance, and the instance had to be up all the time for the writes/reads to succeed regardless of the consistency level used. However, the dynamics change significantly for a multinode cluster as witnessed in the previous chapter. We will create two keyspaces; one with replication factor 2 and the other with replication factor 3. We will then stop a running instance and try out read/write operations with different consistency levels.

Write consistency

Let's create the keyspaces with replication factors 2 and 3 as discussed in the preceding section. To distinguish both the keyspaces, we will include the replication factor within the name. Create keyspaces as follows:

CREATE KEYSPACE "keyspace2" 
WITH REPLICATION = { 
  'class': 'SimpleStrategy', 
  'replication_factor': 2 
}; 
CREATE KEYSPACE "keyspace3" 
WITH REPLICATION = { 
  'class...