Hotel booking (Booking.com / Airbnb)

Browse availability across millions of rooms and book a stay for a date range. Browsing is 95%+ of traffic and tolerates a few seconds of staleness; booking is a small transactional core where two guests must never claim the same last room and a retried checkout must never book twice.

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Duration 45:00

Requirements checklist

Search hotel room types and view nightly availability and rates for a check-in / check-out range.Place a reservation hold on a room type for every night in the stay, complete payment, and confirm or release the hold.View or cancel an existing reservation (returning inventory to the pool).Zero overselling beyond configured overbooking margin: concurrent checkouts for the last room must grant at most one reservation.Exactly-once booking semantics on client retries via an idempotency key.Availability search p99 under ~150 ms; booking checkout p99 under ~500 ms.Browse path stays highly available even if the transactional booking store is failing over.

Clarifying questions

Do guests book a room category (Deluxe King) or a specific physical unit (like Airbnb)?
What is the browse-to-book ratio, and can search results be a few seconds stale?
Do we need a temporary hold window while the user enters payment details?
Should the system support controlled overbooking margins per hotel?

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requirements

Suggested time: about 6 minutes. Clarifies room-type vs specific-room inventory, hold expiry, and intentional overbooking.

Notes for requirements