Sequelize migrations: ensuring rollback safety after schema changes

Problem Overview

Sequelize migration files expose up and down functions, but the framework does not automatically wrap all migration steps in a single transaction across every dialect.

Current Constraints

• When a migration fails during up, only statements executed inside an explicit transaction are rolled back; otherwise partial changes persist.
• DDL support for transactions varies by dialect (PostgreSQL/MySQL support it, SQLite does not fully support schema changes in transactions).
• Sequelize’s sequelize.sync({ alter: true }) helper applies schema changes immediately with no rollback path.

Unresolved Decision

The core question is whether Sequelize should implement a global transaction wrapper for migrations, guaranteeing that a failed migration leaves the database unchanged regardless of dialect.

Specific Questions

1. Should Sequelize automatically wrap every migration’s up and down in a transaction across all supported dialects?
2. What strategies can developers employ to ensure a failed migration does not leave the database in an inconsistent state?
3. How do dialect-specific DDL transaction capabilities influence the feasibility of a universal rollback mechanism?