Book Image

Learning Apache Flink

By : Tanmay Deshpande
Book Image

Learning Apache Flink

By: Tanmay Deshpande

Overview of this book

<p>With the advent of massive computer systems, organizations in different domains generate large amounts of data on a real-time basis. The latest entrant to big data processing, Apache Flink, is designed to process continuous streams of data at a lightning fast pace.</p> <p>This book will be your definitive guide to batch and stream data processing with Apache Flink. The book begins with introducing the Apache Flink ecosystem, setting it up and using the DataSet and DataStream API for processing batch and streaming datasets. Bringing the power of SQL to Flink, this book will then explore the Table API for querying and manipulating data. In the latter half of the book, readers will get to learn the remaining ecosystem of Apache Flink to achieve complex tasks such as event processing, machine learning, and graph processing. The final part of the book would consist of topics such as scaling Flink solutions, performance optimization and integrating Flink with other tools such as ElasticSearch.</p> <p>Whether you want to dive deeper into Apache Flink, or want to investigate how to get more out of this powerful technology, you’ll find everything you need inside.</p>
Table of Contents (17 chapters)
Learning Apache Flink
About the Author
About the Reviewers
Customer Feedback

Broadcast variables

Broadcast variables allow user to access certain dataset as collection to all operators. Generally, broadcast variables are used when we you want to refer a small amount of data frequently in a certain operation. Those who are familiar with Spark broadcast variables will be able use the same feature in Flink as well.

We just need to broadcast a dataset with a specific name and it will be available on each executors handy. The broadcast variables are kept in memory so we have to be cautious in using them. The following code snippet shows how to broadcast a dataset and use it as needed.

// Get a data set to be broadcasted 
DataSet<Integer> toBroadcast = env.fromElements(1, 2, 3); 
DataSet<String> data = env.fromElements("India", "USA", "UK").map(new RichMapFunction<String, String>() { 
    private List<Integer> toBroadcast; 
    // We have to use open method to get broadcast set from the context 
    public void open(Configuration parameters...