PostgreSQL & Node.js Techniques Prevent Inventory Overselling

A common concurrency bug called the lost update problem can cause online stores to oversell limited inventory during high traffic. This occurs when multiple transactions read the same stock level before any of them update it, leading to inaccurate decrements. The article demonstrates the issue using a Node.js and PostgreSQL environment where 50 concurrent purchase requests compete for 10 items. It then presents three solutions: conditional atomic updates, pessimistic locking, and optimistic locking. The appropriate method depends on the specific level of data contention in the application.