Event Sourcing

Event sourcing is a software design pattern where state changes are stored as a sequence of events rather than as snapshots that get updated in place.

Instead of updating a database record directly, every change is recorded as an immutable event (e.g., UserCreated, EmailChanged, AccountDeactivated) which gets inserted as a row in a table. The current state is rebuilt by replaying these events in order.

One thing to note is that in es-entity the events are scoped to a specific type of Entity. Thus they are (by convention) not all written to the same global events table like in some Event Sourcing approaches. Rather each Entity-type gets its own events table - though it is possible to use a global table if desired. Further the events are strictly ordered on a per-entity basis - there are no ordering guarantees across entities.

This can be interpreted as the Entity-type representing a topic and the EntityId playing the role of the PartitionKey that exists in some pub-sub / event-store systems.