How a reservation ledger solves multichannel overselling better than availability formulas

Multichannel overselling is fundamentally a concurrency problem, not a data accuracy issue, meaning real-time availability calculations are prone to race conditions when multiple sales channels query stock simultaneously. A more reliable approach uses an append-only stock movement ledger where reservations are written as database rows with explicit locks, ensuring only one channel can claim a unit at a time. Each reservation must carry a time-to-live expiry to automatically release stock from abandoned checkouts or failed payments, preventing indefinite inventory lockup. Multi-SKU orders must lock rows in a consistent, deterministic sequence to avoid deadlocks, which become critical during high-traffic events like promotions. The method is used in production across three fulfillment warehouses in Shenzhen, Suzhou, and Dongguan, where site-level stock segregation prevents overselling inventory that is physically located far from the destination order.