Shopify · 2026
We replaced Redis with MySQL for inventory reservations—and it scaled
Shopify moved checkout inventory reservations from Redis to MySQL using one row per sellable unit, a bounded pool of 1,000 rows per item/location and SELECT ... FOR UPDATE SKIP LOCKED. The real ceiling was connections held by other checkout code: tagging SQL by business process and measuring hold time in ProxySQL found it, and the cleanup removed 50% of reads and 33% of transactions on the primary.
$5.1 million sales/minute (Black Friday 2025 peak)database migrationdual writesquery optimizationMySQLRedisProxySQL
Discord · 2026
How Discord Automates ScyllaDB Clusters at Scale
Discord's 7-person persistence team replaced fragile Python and bash scripts with the Scylla Control Plane, a Rust framework of idempotent tasks with declared preconditions, composed into YAML workflows. Jobs batch nodes by availability zone with concurrency limits to protect quorum, store their state in SQLite so they resume after interruptions, and send a webhook alert on unrecoverable errors. Operations like standing up shadow clusters and rolling upgrades went from a day and a half of babysitting to under two hours.
dozens of clusters, hundreds of database nodes7-person persistence teamdatabase operations automationidempotent taskszone-aware rolloutsScyllaDBRustYAML