Top 3 Inventory Interview Questions
Browse 3 real-world technical and behavioral interview questions about Inventory. Review scenarios, edge cases, and architectural best practices.
Design ticketing for a 60,000-seat stadium where every seat goes on sale at 10am. How do you sell each seat exactly once?
Selling a specific seat is a uniqueness problem, not a throughput one, so the seat row is the serialisation point and the design lives or dies on the reservation hold: a short expiring claim written atomically, plus a queue in front so the contention never reaches the database at full force.
Two customers try to buy the last item at the same time. How do you handle inventory?
Treat availability as a claim you grant, not a number you read: fold the check and the decrement into one conditional write, hold the winner's claim as a reservation that expires, and choose deliberately how much overselling you accept, because the warehouse and not the database is the real source of truth.
Two people book the last seat at the same moment. Neither is allowed to see a failure after paying. What happens?
Preventing double booking seats means claiming the seat before payment, not racing two payments and reconciling later. A short atomic hold serialises buyers, payment only starts for the winner, and uncertain payment outcomes are settled by reconciliation rather than silent expiry.