Sorted Sets and Leaderboards

What you'll walk away with

Explain the core ideas behind Sorted Sets and Leaderboards
Run the sample Redis command or code and verify its output
Apply the technique correctly to the Tutorial Platform and production scenarios

Build the mental model

A sorted set keeps unique members ordered by floating-point scores. `ZINCRBY` updates scores atomically; `ZRANK` or `ZREVRANK` returns position; score or rank ranges return leaders. Define tie behavior, score precision, season rollover, and member-removal policy up front.

Connect it to a real scenario

Store weekly completed-lesson counts in `leaderboard:lessons:2026-W35` and return the top ten in descending order. PostgreSQL completion events remain the source of truth so the leaderboard can be rebuilt. If the weekly key expires, retain it longer than the reporting requirement.

Members are unique and scores are sortable
Use ZINCRBY for atomic updates
Rebuild leaderboards from a durable source

Try the working example

shell

ZINCRBY leaderboard:lessons:2026-W35 1 user:42
ZINCRBY leaderboard:lessons:2026-W35 3 user:7
ZINCRBY leaderboard:lessons:2026-W35 2 user:9
ZREVRANGE leaderboard:lessons:2026-W35 0 9 WITHSCORES
ZREVRANK leaderboard:lessons:2026-W35 user:42
EXPIRE leaderboard:lessons:2026-W35 7776000

You should see

You get a weekly leaderboard with top users, scores, and user 42's rank.

5-minute try-it

Build a course-specific leaderboard and document product behavior for equal-score ties.

One important caution

Do not use sorted-set floating scores as the source of truth for money or exact decimal accounting.

Redis — Sorted Sets — Redis

Easy traps

Do not use sorted-set floating scores as the source of truth for money or exact decimal accounting.
Validate sample commands on a local or test instance with recoverable data before applying them to production Redis.

Exercise

Build a course-specific leaderboard and document product behavior for equal-score ties.

You'll know it worked when: You get a weekly leaderboard with top users, scores, and user 42's rank.