When engineering point-of-sale and e-commerce platforms handling thousands of concurrent users, traditional naive database queries like `UPDATE products SET stock = stock – 1 WHERE id = 10` will quickly cause row locking cascades, query timeouts, and catastrophic overselling.
In this technical breakdown, we look at the two-phase commit strategy using Redis atomic decrements (`DECR`) as transient reservation tokens, followed by asynchronous batch synchronization back into the primary relational MySQL database.