Immutable Append-Only Logs

Concepts: dmImmutableLogs

The Power of Never Deleting An immutable log is a sequence of events that can only be appended to. You can add new events but never modify or delete existing ones. Kafka topics, database write-ahead logs, and Git commit histories are all immutable logs. This immutability gives you three superpowers: replay, audit, and debugging. Replay: if your downstream aggregation is wrong, fix the logic and replay the log. The events are still there. Audit: every action is recorded with a timestamp and actor. Debugging: reproduce any bug by replaying events up to the point of failure. Designing an Event Schema A well-designed event has: a unique event_id (UUID), an event_type ('order_placed', 'payment_received'), a timestamp (when it happened, in UTC), an actor (who or what caused it), and a payload (t