Design a Distribution-Center Inventory Update Service

Design an ingestion and query service that receives inventory change events from multiple fulfillment centers. For every combination of a fulfillment center and an item, the system must maintain the current stock quantity, a status flag indicating whether the item is sellable (e.g. “available” / “unavailable”), and the timestamp of the last successful update. Readers must be able to retrieve the latest state for any center–item pair with very low latency. The service handles…