Add a column called completed with data type boolean to our existing Todo model
- We want to modify a data schema that already exists
- Data migrations: deal with how we manage modifications to our data schema over time.
Managing changes to the schema
- Mistakes to our database schema are very expensive to make. The entire app can go down.
- When we make a mistake to our data schema, we want to quickly roll back changes.
- We want to test changes before we make them.
Changing data schema
- Migrations deals with how we manage modifications to our data schema, over time.
- Mistakes to our database schema are very expensive to make. The entire app can go down, so we want to
- quickly roll back changes, and
- test changes before we make them
- A migration is a file that keep track of changes to our database schema (structure of our database).
- Offers version control on our schema
- Think of them as git commits.
Upgrades and rollback
- Migrations stack together in order to form the latest version of our database schema
- We can upgrade our database schema by applying migrations
- We can roll back our database schema to a former version by reverting migrations that we applied.
