8.3 Design a Gaming Leaderboard

Two million players online at peak, each finishing a match every five minutes, produce 2,000,000 / 300 s, or about 6,700 score updates per second. While those updates arrive, the same players keep asking three questions that must be answered in milliseconds: who is in the top 100, what is my rank, and who is ranked around me. A leaderboard must answer them correctly under concurrency, survive the end of each season, and keep working when the player base grows tenfold.

A Redis sorted set solves the core problem in a few commands