My Garner Health interview was a system design round.
The first question was to design an appointment booking system where patients could search for doctors and book appointments. I discussed the core Patient, Doctor, and Appointment data models; how to query a doctor's available time slots; and how to book or cancel an appointment. The design also needed to prevent multiple patients from booking the same slot concurrently. We covered the API and database design and how to maintain consistency during appointment booking.
The follow-up introduced a new vaccine that caused a sudden surge of users trying to reserve vaccination appointments. I discussed scaling the system with a load balancer and horizontal scaling, caching popular doctors and appointment availability, and scaling the database with options such as read replicas or sharding. Other directions included separating booking writes from query traffic and using a queue or asynchronous processing to absorb traffic spikes.
For popular vaccine appointments, I also discussed throttling or rate limiting. The design still had to prioritize concurrency control during booking so that it would not oversell availability or double-book a slot. We also covered monitoring, autoscaling, and failure handling. Overall, this was a practical system design interview focused on booking consistency under concurrency and scalability during a sudden traffic spike.
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