The event sourcing pattern is a well-known pattern is gaining widespread adoption among microservices developers as a way of adhering to the "database per service" principle.

Event sourcing replies upon an append-only store to record the entire sequence of actions taken upon system rather than a more traditional relational database. It is often combined with the CQRS that uses materialized views to convert event-based data from one (or more) sources into a format that is more suitable for querying.

In this talk, we will build a simple microservice application that demonstrates the benefits of combining Flink SQL with Apache Pulsar to pre-calculate these materialized views and continuously update them when new events arrive.