Design a device owner lookup service

## Scenario Your server receives a stream of events from clients. Each event contains: - `user_id` - `device_id` - `timestamp` (event time) A device may be associated with different users over time (e.g., shared device, logout/login, resale). ## Core requirement Build a backend service that supports: - `get_device_owner(device_id) -> user_id` Returns the **current owner** of the device. Assume “current owner” means the `user_id` from the **latest event by timestamp** for that `device_id`. ## Constraints / concerns to address - Events may arrive **out of order**. - Clients may retry → **duplicate events**. - Large scale (many devices; high write QPS; low-latency reads). - Define behavior for ties (same timestamp) and missing devices. ## Deliverables - API design (ingestion + query) - Data model - Storage and indexing - How you handle out-of-order/duplicate events - Consistency guarantees and trade-offs - Monitoring and operational considerations