Challenge 15: Capstone: sales rank by category
Shoppers read category rankings 27,000 times a second, and 3,000 purchases a second update them. Half of all traffic concerns one category, the current best-seller list. Keep every partition under its capacity, with p99 under 200 ms, surviving the loss of any instance, for at most 3,000 USD a month.
Traffic demand30,000 RPS90% reads, 10% writes
p99 latency target≤ 200 msSlowest 1% of requests
Availability≥ 99.99%N-1 failure survival (0 drops)
Monthly cloud budget≤ 3,000 USDA month, everything included