database-migrations

Zero-downtime database migrations in PostgreSQL use concurrent index creation and expand-contract patterns to apply schema changes without locking tables. This separates schema changes from data backfills to maintain backward compatibility.

The expand-contract pattern is a zero-downtime migration technique that separates schema changes from data migrations into backward-compatible phases. It allows adding or removing columns safely by expanding the schema first, then contracting it after deployment.

Yes, these database migration workflows support common ORMs including Prisma, Drizzle, Kysely, Django, TypeORM, and golang-migrate. Each tool has dedicated guidance for applying and deploying safe, reversible migrations.

Safe data backfills in MySQL require executing updates in batches to avoid locking tables and causing downtime. This approach enforces migration safety checks and separates data migrations from schema changes to prevent deployment drift.

Adding a column without locking the database requires non-blocking index creation and an expand-contract migration strategy. This ensures forward migrations remain backward-compatible and explicit down migrations are available for reversibility.

Separating schema changes from data migrations prevents deployment drift and avoids locking tables during backfills. This practice enforces migration safety checks, ensuring zero-downtime transitions across PostgreSQL and MySQL environments.