Hot stories ranking
Your task
Design a 'top stories' / hot-ranking system for a community link-aggregator (like a tech-news front page). Stories are ranked by a score combining votes, comments, and age (newer rises, then decays). Scale: 5M users, 50k new stories/day, the front page is read millions of times/hour, and a story's rank must update within ~1 minute of new votes.
It covers
- Leaderboard
- Windowing
- Consistency