Architect
Not everything needs consensus
A multiplayer game keeps player accounts and purchases in a distributed SQL cluster spread over three regions, and that is the right call: money must never diverge. But the game servers also write every match event into the same cluster, 30,000 writes per second that only feed replays and statistics. The bill has tripled and purchases got slow. Bring the platform under 15,000 dollars a month with a p99 under 250 ms.
Every write to the accounts cluster is committed by consensus across regions, which costs cross-region round trips and three copies of the work. Match events are append-only, keyed by match, read a few times for replays, and losing a region's worth of them for a while is acceptable. The accounts cluster stays: resize it, but do not replace it.
What your design must achieve
- Monthly bill < 15,000 $
- Latency p99 < 250 ms
- Availability ≥ 99.95 %