Using persistence query
Akka persistence query is a helper module in the Akka persistence ecosystem that gives visibility into the journal events. Akka persistence query provides means to run asynchronous queries against the journal by using Akka Streams. Akka persistence query defines a set of predefined queries to analyze the log of events. Akka persistence query has a very loose API on purpose, so it is common to find different journal plugins with slightly different implementations. In this recipe, we will review the different predefined queries and see what each query is used for.
Getting ready
This recipe does not have any prerequisites. However before going through this recipe, it is required to understand what event adapters are in the Akka persistence context. Event adapters help to detach the data model from the domain model completely. This might be helpful in scenario where your data model evolves over time or you want to use a different format when storing the events in the journal...