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)

Recording analytics observations


At this point, we've explored structuring both discrete and aggregate analytics data and looked at accessing that data. However, to have interesting data aggregates to access, we first need to record our observations.

Updating a counter column

The daily_status_update_views table introduces a new type of column: the counter column. Counter columns store integer values, just like int and bigint columns; however, unlike a normal data column, counter columns are always incremented or decremented rather than having a value set directly.

We've currently got two tables to store usage data: status_update_views to store raw view observations, and daily_status_update_views to store views by day. We'd like to record that one of alice's status updates was viewed on the Web on October 5, 2014 at 3:12 P.M. EDT:

INSERT INTO "status_update_views" ( 
  "status_update_username", "status_update_id", 
  "observed_at", "client_type" 
) VALUES ( 
  'alice', 76e7a4d0-e796-11e3-90ce...