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)

JSON support


JSON is short for JavaScript Object Notation and is a way to store information in an organized, easy-to-access manner. In a nutshell, it gives us a human-readable collection of data that we can access in a really logical manner. It is the most commonly used data format for client/server communication.

Starting with Cassandra 2.2, JSON support was added to the features list of Cassandra. This is an extension of CQL, which makes it easier to work with JSON documents. The SELECT and INSERT statements now include a JSON-focused variant, and two new native functions have been added to convert to and from JSON.

INSERT JSON

The INSERT statement accepts a JSON variant. Suppose we want to insert some JSON data into our user_status_updates_by_datetime table, we can do it in the following way:

INSERT INTO "user_status_updates_by_datetime"
JSON '{"username": "alice", "status_date": "2016-11-24", "status_time":
"13:35:20.123456", "body": "Alice Update 7"}';

Now, if you run the query SELECT ...