#concurrency

Actor-per-Entity vs Postgres Optimistic Locking: A Seat-Reservation Bake-off

I ran the same hot-key seat reservation workload two ways: Postgres with a version column and retries, and a single actor per seat. The actor design did not scale better — it moved the hard problem from concurrency control to routing and rebalance correctness, and that trade was the easier one to reason about under hot keys.