YOUR BRIEF
What to work through
Work through a game leaderboard as a spoken system design interview. Start by clarifying the scope, sketch a working design and explain the trade-offs behind your choices.
- A player gets a point for each match they win
- Show the top 10 players of the monthly tournament
- Show any player their own rank
- Bonus: show the four players above and below a player
BEFORE YOU START
Constraints to discuss
- Ranks update in near real time, not in a nightly batch
- 2,500 score updates a second at peak
- 25 million players a month on the board
- Only game servers can change a score
Need a starting point?
Watch for these common gaps as you prepare:
- Letting the game client post its own score, open to anyone who edits the request
- Computing every rank with a SQL count over the whole table
- Hash sharding without noticing that every rank and top 10 becomes a scatter-gather
- Redis with no replica, no persistence and no record of wins to rebuild from
Why this question is in the collection
These sources connect the problem to company interview reports or preparation guides. They do not guarantee what a company will ask you.