System Design Interview: Design Ticketmaster w/ a Ex-Meta Staff Engineer

Step-by-Step Tutorial: Designing a Ticket Booking Service like Ticketmaster

1. Understand the Requirements:

   • Define the functional requirements (features like viewing events, searching for events, and booking tickets) and non-functional requirements (qualities like scalability, availability, reliability, and fault tolerance).
   • Consider unique challenges like prioritizing consistency for booking tickets and high availability for searching and viewing events.

2. Define Core Entities:

   • Identify core entities like events, venues, performers, and tickets that will be persisted and exchanged through APIs.

3. Design APIs:

   • Create APIs to satisfy functional requirements:
     • Viewing an Event: Implement an API that takes an event ID and returns event details.
     • Searching for an Event: Develop an API that allows searching by terms like type, date, and location.
     • Booking a Ticket: Design a two-phase process with endpoints to reserve and confirm ticket bookings.

4. High-Level Design:

   • Implement a microservices architecture with an API Gateway routing requests to the appropriate microservices.
   • Utilize databases like PostgreSQL for storing core entities such as events, venues, performers, and tickets.

5. Deep Dive into System Enhancements:

   • Optimize Search with Elasticsearch: Implement Elasticsearch for low-latency search by creating inverted indexes for quick document retrieval.
   • Real-Time Seat Availability Updates: Use long polling or Server-Sent Events (SSE) to update seat availability in real-time for a better user experience.
   • Introduce a Virtual Waiting Queue: Implement a virtual waiting queue to manage high traffic during popular events and improve user experience by controlling access.

6. Scaling Strategies:

   • Cache Immutable Data: Use Redis to cache static data like events, venues, and performers to reduce the read load on the primary database.
   • Evaluate Sharding: Consider sharding the database based on read/write ratios and scalability requirements to optimize performance.

7. Conclusion:

   • Ensure the design meets all functional and non-functional requirements.
   • Reflect on the design decisions made and consider any potential improvements or optimizations.

8. Feedback and Iteration:

   • Solicit feedback on the design from peers or mentors to identify areas for improvement.
   • Iterate on the design based on feedback to enhance the system's efficiency and effectiveness.

By following these steps, you can effectively design a ticket booking service like Ticketmaster, considering key aspects such as requirements, entity modeling, API design, system enhancements, scaling strategies, and overall system architecture.