Advanced
Shard the write path
A ride-hailing app records every driver's position. Writes have outgrown the biggest database instance available. Scale them out.
40,000 position updates per second at peak. Some cities are much busier than others, so a poor shard key creates hot shards.
What your design must achieve
- Availability ≥ 99.9 %
- Latency p99 < 200 ms
- Infrastructure cost per month < 60,000 $ bonus