This chapter covers
- Understanding ksqlDB
- More about streaming queries
- Building streaming applications with SQL statements
- Creating materialized views over streams
- Using ksqlDB advanced features
At this point in the book, we’ve learned about several components of the Kafka event streaming platform—Kafka Connect for integrating external systems and Kafka Streams for building an event streaming application. These two components together form the bedrock of building event streaming applications. In this chapter, you will learn about ksqlDB, which allows you to use those components by writing SQL to construct an event streaming application. ksqlDB is a “streaming database purpose-built for streaming applications” (https://ksqldb.io/). It will enable you to build powerful streaming applications with a few SQL statements.
So why would you use ksqlDB? For starters, it vastly simplifies the application development process. With ksqlDB, you’re not working with code or configuration files. You write your SQL queries and execute them, which launches a continually running application where you can get instant notification of events.