Design Uber Surge Pricing

1. Problem Statement

2. Architecture Discussion Map

Use this as one discussion aid, not a single correct answer. Your design should follow from the requirements, scale, and trade-offs you establish.

graph TD
    A[Rider/Driver Apps] -->|WebSocket/gRPC| B(API Gateway)
    B --> C[Location Ingestion Service]
    C -->|Kafka Topic: Locations| D[Flink Stream Processor]
    D -->|Aggregates per S2 Cell| E[(Redis: Heatmap Cache)]
    E -.->|Pulls TTL Data| F[Pricing Engine]
    F -->|Updates| G[(Cassandra: Price History)]
    F -->|Pushes Real-time Price| B

3. Key Focus Areas

• 1
  Geospatial Indexing (Hierarchical Cells or Geohashes)
• 2
  Supply/Demand Aggregation (Streaming)
• 3
  Consistency (Price Lock)
• 4
  Latency (Calculate price < 50ms)
• 5
  Feedback Loop (Throttling)

4. What the Interviewer Looks For

The interviewer probes these areas, and the report grades the interview against them.

• Requirements and estimation
• Geospatial bucketing and aggregation
• Pricing computation and market stability
• Quote serving and price lock
• Reliability, abuse, and audit