How we deploy zero-downtime database migrations to a Part 11 validated environment

Our customers run validated processes on Quays. Their auditors expect formal change control. Our engineers want to ship continuously. These goals appear incompatible. They’re not.

The expand-contract pattern, validated

• Phase 1 (expand): add new schema in a backwards-compatible way.
• Phase 2 (migrate): dual-write to old and new structures.
• Phase 3 (cutover): flip reads to new structure behind a feature flag.
• Phase 4 (contract): retire old structure once feature flag is 100%.

How this satisfies validation

Each phase is its own validated change package, with its own testing protocol and rollback. Customers see zero impact, auditors see complete documentation.