database-migrations

You perform a zero-downtime migration by separating structural changes from data backfills and applying an expand-contract pattern. This approach sequences forward-only schema steps and validates them before finalizing the PostgreSQL column addition.

The expand-contract pattern is a zero-downtime strategy that separates database migrations into independent deployment phases. It expands the schema first, updates application logic, and contracts obsolete structures later to ensure safe, reversible schema evolution.

You handle data backfills by separating them entirely from structural schema changes so they deploy and recover independently. This separation allows large data transformations to run safely alongside live traffic without blocking table access during the migration.

Yes, separating schema and data steps is required for forward-only production sequencing in Django or Prisma migrations. This requirement ensures safe ORM workflows for adding columns, indexes, or backfills while maintaining explicit rollback guidance.

The best way to plan a safe rollback is to require forward-only production sequencing with explicit recovery guidance for each step. By isolating schema changes from data transformations, you ensure both structural and data edits can be independently reversed during migration.