Classic Airbnb question, probably the most predictable thing they could have asked.
Start by clarifying functional and non-functional requirements, then design a high-level architecture covering core entities like users, listings, and bookings. Dive into data modeling for availability and concurrency, and discuss trade-offs around consistency, scalability, and user experience.
Pro tip: Emphasize how you handle double bookings and race conditions using techniques like optimistic locking or distributed transactions, as this is a critical challenge in booking systems.
Ask questions to understand scope: Is this for hotels, flights, or home rentals? What are the key features (search, booking, payment)? What are the scale and consistency requirements?
Sketch the main components: client apps, API gateway, services (user, listing, booking, payment), databases, and caches. Define the core data entities and their relationships.
Design schemas for listings, availability calendars, and bookings. Discuss how to efficiently query availability and handle updates, considering time zones and date ranges.
Address race conditions and double bookings. Compare approaches like pessimistic vs. optimistic locking, distributed transactions, and eventual consistency with compensating actions.
Discuss scaling reads/writes, caching strategies, sharding, and trade-offs between consistency, availability, and latency. Mention monitoring and failure handling.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.