Hi all,
I wrote up a post on Django’s migrations. I cover a high level overview of how they work, how you can get into trouble with them and how to recover (beyond creating a new database). Let me know what you think!
It is a bit long, so here’s the TLDR from the post.
Toolkit:
-
manage.py makemigrations: Creates the migration files -
manage.py migrate: Runs the migrations (changes the database) -
manage.py showmigrations --verbosity 2: Tells you what migrations have been applied and when -
manage.py sqlmigrate <app> <migration>: Tells you what SQL will run for a migration -
manage.py dbshell: Opens up a database SQL shell (we used sqlite3 directly)
Strategies:
- Make a backup of your database before changing it
- Commit your migrations
- Before changing/deleting a migration file, make sure it’s unapplied in every environment first
- When migrate fails, investigate the current database schema and the generated SQL from the migration
- Use SQL diffing tools to compare the schema with a known good database