Migration (Database)
A database migration is a controlled change to your database structure — adding a table, renaming a column, or creating a relationship. Migrations track changes in files so you can apply them consistently across environments. For vibe coders, AI generates migrations when you modify your data model, but understanding them prevents data loss.
Example
You add a 'bio' field to your User model. Running 'npx prisma migrate dev' creates a migration file that adds the bio column to your users table. This same migration runs on your production database during deployment, keeping everything in sync.
Migrations are version control for your database. Just like Git tracks code changes, migrations track database structure changes.
Why Migrations Exist
You can't just edit a database like a text file:
- Data already exists in the tables
- Other environments need the same changes
- You need to undo changes if something goes wrong
- Team members need to stay in sync
Migrations solve all of this.
How Migrations Work
- Change your schema — Modify the data model
- Generate migration — Tool creates a migration file describing the change
- Review — Check that the migration does what you expect
- Apply — Run the migration to update the database
- Commit — Save the migration file in version control
Common Migration Operations
| Operation | Example |
|---|---|
| Add table | Create a new products table |
| Add column | Add avatar_url to users |
| Remove column | Drop unused legacy_field |
| Add index | Speed up queries on email |
| Add relationship | Connect users to posts |
Migration Dangers
Always be careful with:
- Dropping columns — Data is permanently deleted
- Renaming columns — Can break existing code
- Changing types — May lose data precision
- Production migrations — Test in staging first
AI and Migrations
AI generates migrations automatically when you change your schema. Always:
- Read the generated migration before applying
- Check for data-destructive operations
- Back up your database before risky migrations
- Test migrations on a copy of production data
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Related Terms:
Emergent — An agentic vibe-coding platform that builds production-ready apps