Activity Tracker (Strava)
Difficulty: Medium
What It Tests
GPS data ingestion, activity analysis, leaderboards, time series data.
Topics Covered
- Time Series Databases
- Database Design: SQL vs NoSQL
- Caching
- API Design
- Wide-Column Stores (Cassandra)
Hello Interview Breakdown
Read the full Hello Interview breakdown →
Approach Hints
- Ingest GPS track points as time-series data (Cassandra or InfluxDB)
- Compute activity statistics (distance, pace, elevation) async after upload
- Serve segment leaderboards from precomputed Redis sorted sets
- Store activity summaries in PostgreSQL for complex queries