Revised database Sharding trade-offs and did a massive deep dive into Ticketmaster real-time UI synchronization:
Explored client-update mechanisms: Short Polling (expensive, high overhead), Long Polling (holding requests open, better but stateful), and Server-Sent Events (SSE) (unidirectional stream, ideal for real-time seat map changes).
Reviewed the virtual waiting queue pattern (Redis Sorted Set) to shield the booking service from heavy traffic rushes like Taylor Swift/World Cup ticket sales.