Data, login & progress
Module 4 / Lesson 4

Migrations and lasting history

Change your schema without losing learning records.

16 minutes

A schema evolves

Adding bookmarks or review dates changes the data model. Record changes in ordered migrations so a fresh installation and an existing database reach the same structure. Avoid silently rewriting old migration history.

Prove the upgrade

Test an upgrade from a small earlier database containing synthetic progress. Check the data afterward and practice restore using a disposable environment. A backup is useful only if you can recover from it.