database-migrations

Zero-downtime database migrations use the expand-contract pattern to separate schema changes from data backfills, ensuring concurrent operations do not lock production tables. This approach applies non-locking schema alterations across PostgreSQL and MySQL to maintain continuous availability.

The safest way to backfill data when adding columns with defaults is to separate the data migration from the schema alteration, batching the backfill to avoid locking. This process runs first in staging to monitor issues before executing the production database migration.

Yes, this database migration approach works with Prisma, Django, Drizzle, Kysely, and golang-migrate ORM layers. It provides patterns for concurrent indexes and reversible schema changes that integrate directly with these specific ORM tools.

Writing reversible UP and DOWN migrations requires defining a rollback plan for every schema alteration and data move. This enforces migration safety by ensuring each deployment process includes tested, auditable DOWN migrations that reverse the exact changes applied.

Database migrations cause production outages when schema changes lock tables or break application compatibility. Prevent production drift and downtime by applying a migration safety checklist with non-locking changes, concurrent operations, and separate data migrations across PostgreSQL and MySQL.