Migration Principles

Safe migration strategy for zero-downtime changes.

Safe Migration Strategy

For zero-downtime changes:
│
├── Adding column
│   └── Add as nullable → backfill → add NOT NULL
│
├── Removing column
│   └── Stop using → deploy → remove column
│
├── Adding index
│   └── CREATE INDEX CONCURRENTLY (non-blocking)
│
└── Renaming column
    └── Add new → migrate data → deploy → drop old

Migration Philosophy

• Never make breaking changes in one step
• Test migrations on data copy first
• Have rollback plan
• Run in transaction when possible

Serverless Databases

Neon (Serverless PostgreSQL)

Turso (Edge SQLite)