ksqlDB Fundamentals: How Apache Kafka, SQL, and ksqlDB Work Together ft. Simon Aubury

What is ksqlDB and how does Simon Aubury (Principal Data Engineer, Thoughtworks) use it to track down the plane that wakes his cat Snowy in the morning? Experienced in building real-time applications with ksqlDB since its genesis, Simon provides an introduction to ksqlDB by sharing some of his projects and use cases. 

ksqlDB is a database purpose-built for stream processing applications and lets you build real-time data streaming applications with SQL syntax. ksqlDB reduces the complexity of having to code with Java, making it easier to achieve outcomes through declarative programming, as opposed to procedural programming. 

Before ksqlDB, you could use the producer and consumer APIs to get data in and out of Apache Kafka®; however, when it comes to data enrichment, such as joining, filtering, mapping, and aggregating data, you would have to use the Kafka Streams API—a robust and scalable programming interface influenced by the JVM ecosystem that requires Java programming knowledge. This presented scaling challenges for Simon, who was at a multinational insurance company that needed to stream loads of data from disparate systems with a small team to scale and enrich data for meaningful insights. Simon recalls discovering ksqlDB during a practice fire drill, and he considers it as a memorable moment for turning a challenge into an opportunity.

Leveraging your familiarity with relational databases, ksqlDB abstracts away complex programming that is required for real-time operations both for stream processing and data integration, making it easy to read, write, and process streaming data in real time.

Simon is passionate about ksqlDB and Kafka Streams as well as getting other people inspired by the technology. He’s been using ksqlDB for projects, such as taking a stream of information and enriching it with static data. One of Simon’s first ksqlDB projects was using Raspberry Pi and a software-defined radio to process aircraft movements in real time to determine which plane wakes his cat Snowy up every morning. 

Simon highlights additional ksqlDB use cases, including e-commerce checkout interaction to identify where people are dropping out of a sales funnel.