Migrations

Your schema is the foundation of everything. Bad schema decisions are expensive to fix later. Good ones make your application easier to build and scale. Why Migrations? A migration is a versioned SQL file that changes your schema. Instead of running ALTER TABLE manually in production and hoping everyone does the same, migrations track every schema change in version control. Every team member applies the same migrations in the same order. Your CI pipeline applies them automatically. Rollbacks are possible. ...

The Compose tutorial covered basic Room: one entity, one DAO, simple CRUD operations. That is enough for a notes app. Real apps need more. Users update their app and you need to migrate the database without losing data. You have notes with tags — a many-to-many relationship. Users search through thousands of notes and expect instant results. This tutorial covers the advanced Room patterns you need for production apps. Prerequisites: Compose Tutorial #13: Room basics and Kotlin Tutorial: Flow. ...