Trending topics with velocity detection

DesignHard45 minMeta and Google style

Your task

Design a real-time trending-topics system for a global social platform processing 500k events/sec (posts, hashtags, shares). 'Trending' should surface topics with abnormal velocity, not just high absolute volume, refreshed every 60s, regionalized, and resistant to coordinated spam bursts.

It covers

  • Count min sketch
  • Time decay
  • Spike detection