8.4 Leaderboard Sharding and Reliability

Score updates for lb:season42:global arrive at about 6,700 per second, and the previous lesson kept the whole board in one sorted set. Ties are broken by an inverted timestamp packed into each score. Every score event is written first to a durable log and a database, so the board in Redis is derived from them.

This lesson takes that board to 100 million players. It splits the board across shards while keeping ranks exact or explicitly approximate, and then covers hot reads, durability, idempotent submissions and anti-cheat.