A game needs a live leaderboard for 10 million players: the top 100 and any player's rank, updated on every score. What fits best?

Options

• ✓ A Redis sorted set, with O(log n) updates and rank queries Correct
• ✗ An SQL ORDER BY score query on every page view
• ✗ A HyperLogLog of scores
• ✗ A Bloom filter of top players

Why

A sorted set keeps members ordered by score as they change, so ZADD, ZREVRANK and ZRANGE key 0 99 REV stay fast. Sorting 10 million rows on each request does not scale.

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