Book Image

Building Big Data Pipelines with Apache Beam

By : Jan Lukavský
Book Image

Building Big Data Pipelines with Apache Beam

By: Jan Lukavský

Overview of this book

Apache Beam is an open source unified programming model for implementing and executing data processing pipelines, including Extract, Transform, and Load (ETL), batch, and stream processing. This book will help you to confidently build data processing pipelines with Apache Beam. You’ll start with an overview of Apache Beam and understand how to use it to implement basic pipelines. You’ll also learn how to test and run the pipelines efficiently. As you progress, you’ll explore how to structure your code for reusability and also use various Domain Specific Languages (DSLs). Later chapters will show you how to use schemas and query your data using (streaming) SQL. Finally, you’ll understand advanced Apache Beam concepts, such as implementing your own I/O connectors. By the end of this book, you’ll have gained a deep understanding of the Apache Beam model and be able to apply it to solve problems.
Table of Contents (13 chapters)
1
Section 1 Apache Beam: Essentials
5
Section 2 Apache Beam: Toward Improving Usability
9
Section 3 Apache Beam: Advanced Concepts

Understanding windowing semantics in depth

In Chapter 1, Introducing Data Processing with Apache Beam, we introduced the basic types of window functions. To recap, we defined the following:

  • Fixed windows
  • Sliding windows
  • Global window
  • Session windows

We also defined two basic types of windows: key-aligned and key-unaligned. The first three types (fixed, sliding, and global) are key-aligned, and session windows are key-unaligned (as in session windows, each window can start and end at different times for different keys). However, what we skipped in Chapter 1, Introduction to Data Processing with Apache Beam, was the fact that we can define completely custom windowing logic.

The Window.into transform accepts a generic WindowFn instance, which defines the following main methods:

  1. The assignWindows method, which assigns elements into a set of window labels.
  2. The isNonMerging method, which tells the runner whether the WindowFn instance defines merging...