Design a Ticketing System (Ticketmaster)
Design a Ticketmaster-style ticketing platform that sells reserved seats for concerts and sports events, with the central challenge being a flash onsale where 1M users compete for 50K seats in five minutes. The interview centerpiece is the seat reservation lock: each unique seat (Section A, Row 12, Seat 7) cannot be split or sub-bucketed like fungible inventory, so contention is unavoidable. We cover seat-level pessimistic holds with TTL, the virtual waiting room that randomizes queue position to absorb flash demand fairly, anti-bot defenses, dynamic pricing tiers, and the read-replica explosion that interactive seat maps cause.
