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)

Driver policies


The Java driver provides several policies to configure behavior. Some of the policies are as follows:

  • Load-balancing policy: This determines which Cassandra host to contact for each query. The policy is made aware of any changes in the cluster topology. They ensure that downed nodes are excluded and decommissioned, or removed nodes are removed from the connection pool.
  • Retry policy: This determines the course of action whenever failures occur. It's usually triggered when a timeout or host unavailable exception happens. This minimizes exception handling from our side by automating query retry of failures.
  • Reconnection policy: This policy decides how often reconnection to a dead node is attempted.

Load-balancing policy

As the name implies, the driver forwards queries to hosts based on the load-balancing policy chosen. Usually, this distributes the queries evenly amongst the nodes in the cluster. Java driver provides several load-balancing policies. You can create your own load-balancing...