Shopify replaced Redis with MySQL for inventory reservations–and it scaled

The Story At A Glance

• • Shopify moved inventory reservations from Redis to MySQL to ensure transactional correctness.


• • The new system uses a bounded pool of rows and MySQL 8's SKIP LOCKED to handle high concurrency.


• • This change eliminated the risk of overselling caused by split state between two different systems.

Context
Shopify struggled with atomicity because reservation data and inventory ledgers lived in separate databases. Moving everything into a single MySQL transaction solved the synchronization failures.

Christian Perspective
Truth and accuracy are fundamental virtues that extend even to digital commerce. This technical shift prioritizes integrity by ensuring that what is promised to a customer is actually available in the ledger. Avoiding the sin of falsehood in business transactions reflects a commitment to honest dealings.

Implications
Reliable commerce is a cornerstone of a stable and prosperous nation. When systems function with precision,