unknown

Event sourcing is an architectural pattern that stores all state changes as immutable events in an append-only log, rather than just the current state. This enables complete audit trails, point-in-time state reconstruction, and natural integration with CQRS. The pattern uses hydration to rebuild current state from events, snapshots to optimize performance, and materialized views for efficient queries. In CQRS systems, the command side generates events while the query side listens to these events to update read models, creating a scalable and auditable architecture.