Convex Migrations

Convex handles schema changes without migration files. You deploy new schemas instantly, but here's the thing: existing data doesn't automatically transform. This skill teaches the pattern of adding optional fields first, backfilling with batched mutations using pagination cursors, then making fields required once data is migrated. It covers the full cycle for adding fields, renaming (copy then delete), removing deprecated data, and adding indexes. The batched backfill pattern with scheduler is key since you can't just run ALTER TABLE. If you're moving from traditional databases, the zero-downtime approach feels different but works well once you internalize that schema and data migration are separate steps.