Database Migration

This skill enables an AI agent to manage versioned database schema changes through migration frameworks. The agent creates forward and rollback migration scripts, handles data backfills during schema changes, ensures zero-downtime deployments with safe migration patterns, and integrates migration workflows into CI/CD pipelines. It supports major tools including Alembic (Python/SQLAlchemy), Prisma Migrate (TypeScript/Node), Flyway (Java/SQL), and Knex (JavaScript).

Workflow

1. Assess the schema change: Analyze the requested change — adding columns, creating tables, modifying constraints, renaming fields, or transforming data. Classify the change as backward-compatible (additive) or breaking (destructive) to determine the deployment strategy. Breaking changes require a multi-phase migration approach.

2. Select the migration tool: Choose the appropriate migration framework based on the project's tech stack. Use Alembic for Python/SQLAlchemy projects, Prisma Migrate for TypeScript/Prisma projects, Flyway for Java or SQL-first workflows, and Knex for Node.js/Express projects. Ensure the tool is initialized and connected to the target database.

3. Generate the migration script: Auto-generate a migration from schema diffs where supported (Alembic autogenerate, Prisma migrate dev), then review and edit the generated script. Add explicit rollback (downgrade) logic. For data backfills, include the data transformation within the migration to keep schema and data changes atomic.

4. Test in a staging environment: Apply the migration against a staging database that mirrors production. Verify that the migration applies cleanly, that existing queries still work, and that the rollback restores the previous state. Run the application's test suite against the migrated schema.

5. Deploy with zero-downtime strategy: For production, use expand-and-contract migrations. Phase 1: add new columns/tables (expand) without removing old ones. Phase 2: deploy application code that writes to both old and new structures. Phase 3: backfill data. Phase 4: deploy code using only new structures. Phase 5: remove old columns/tables (contract). This ensures no downtime and safe rollback at each phase.

6. Verify and monitor: After deployment, verify migration status with the framework's status command. Monitor application logs and database performance for regressions. Confirm all migration metadata is recorded in the framework's version table.

Supported Technologies