The text delves into the concept of event sourcing, particularly derivative event sourcing, and its application in complex systems with multiple order services, such as those at the Cabot Cove Detective Agency. It explores the challenges of integrating legacy systems with modern data streaming solutions like Apache Kafka, especially when dealing with technical debt and diverse technical environments. The text explains how change data capture (CDC) can be used to derive events from existing databases, allowing for seamless integration across various services. It highlights the use of tools like Oracle GoldenGate and Debezium to facilitate this process and describes how Kafka Streams can transform and aggregate these events into a central event service. The piece emphasizes the importance of designing flexible event schemas and the benefits of decoupling event processing, which can enhance system resilience and scalability. It concludes by inviting readers to explore more complex scenarios and best practices in derivative event sourcing through additional resources and talks.