database-migrations

To add a non-nullable column without locking a PostgreSQL table, you must use a multi-step zero-downtime migration strategy. This involves adding the column as nullable, backfilling the data, and finally enforcing the constraint after deployment.

A zero-downtime database migration is a schema evolution technique that applies changes without interrupting service. It decouples schema updates from application deployments, often using concurrent index creation and backfilling strategies to prevent table locks.

Yes, the guidance covers tooling integration patterns for Prisma, Drizzle, Django, and golang-migrate. It provides best practices for safe schema changes and data migrations specific to these ORM environments.

The best way to backfill data during a schema change is to batch the updates in small chunks. This approach minimizes table locks and transaction overhead, ensuring the data migration remains safe and reversible.

Concurrent index creation prevents downtime by allowing the database to continue serving read and write operations while the index builds. This avoids the exclusive table lock required by standard index creation.

You should avoid direct schema migrations when changes involve large tables or non-nullable constraints that cause table locks. Instead, use reversible patterns and incremental deployments to prevent service interruptions.