Restaurant Reservation System

September 4, 2022 6:00 PM PDT

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The meeting focused on designing a Restaurant Reservation System, discussing its functional and scaling requirements, system architecture, and potential challenges related to concurrency and database management. The interviewee presented their design and received feedback on various aspects of the system.

Functional Requirements

• Register Restaurant
• Search for Restaurants
• Make Reservations
• Manage Reservations: View, modify, and cancel reservations.
• Reservation Priority: Ensure first-come-first-serve during high traffic.

Scaling Requirements

• High Availability
• Low Latency
• Consistency
• Highly Concurrent: Support for 60,000 restaurants and 1 billion bookings per year.

System Design

External APIs

• Restaurant Management Service
• Database: SQL database preferred for transaction support.

Database Tables

1. Restaurant Table

   • Location
   • Hours
   • Geohash

2. Reservation Table

   • Restaurant ID (FK)
   • Customer ID (FK)
   • Reservation ID
   • Table ID
   • Party Size
   • Date/Time
   • Status

3. Seating Tables/Inventory

   • Table ID
   • Reservation ID
   • Time/Date
   • Party Size

API Endpoints

• Create Restaurant: POST /restaurantID/
• Make Reservation: POST /restaurantID/time/customerId/size
• Get Available Restaurants: GET /available/restaurants/location/type

Concurrency Management

• UI Prevention: Grey out buttons for unavailable reservations.
• Idempotent ID: Prevent double bookings.
• Database Constraints: Ensure sufficient inventory.
• Locking Mechanisms:
  • Pessimistic Locking: May lead to deadlocks.
  • Optimistic Locking: Use version numbers to manage reservations.

Cache Management

• Cache Consistency: Update cache quickly during database updates.
• Control Flow:
  1. User attempts to reserve a table.
  2. Check cache; if miss, fetch from database.
  3. Handle concurrent requests appropriately.

Feedback and Suggestions

• Strengths:

  • Good knowledge of components and system design.
  • Effective use of diagrams to illustrate concepts.

• Areas for Improvement:

  • Focus more on core requirements and avoid unrelated components.
  • Practice mental math for estimations.
  • Be more assertive in design choices.

Additional Considerations

• Microservices vs. Monolithic Architecture: Discussed the benefits of separating databases for different services.
• Handling Peak Load: Consideration for high traffic during holidays or popular times.
• Overbooking Strategy: Allow some tables for walk-ins while managing reservations.

Audience Questions

• Discussed the feasibility of reserving specific tables versus general reservations.
• Explored concurrency issues and locking strategies.
• Considered the implications of unique constraints and potential solutions for managing simultaneous bookings.

This structured approach provides a comprehensive view of the Restaurant Reservation System design discussion, highlighting key points and technical considerations.