Django Migrations: Pitfalls and Solutions with Benjamin Zagorsky - DjangoCon US 2022

Five key takeaways:

• Back up your database regularly, as database backups allow for time travel and can salvage data in case of issues.
• Migrations should always include both a forwards and backwards function to ensure reversibility.
• Backwards compatible migrations are crucial for successfully deploying changes to a database, without downtime.
• run Python is a powerful tool in Django that can be used to refactor and optimize migrations.
• Avoid setting null fields and instead start with nullable fields and then populate them later, as this makes reversible migrations easier to implement.

Top five recommendations:

• Backwards compatibility is crucial for successful deployments.
• Have a scheduled downtime for maintenance.
• Set up a migration recorder for quick debugging.
• Use run Python for refactoring and optimization of migrations.
• Regularly back up your databases.

Additional points:

• Scheduled downtime is essential for maintenance and successful deployments.
• Migrations should be ran in a specific order to avoid conflicts with other migrations.
• Django doesn’t guarantee that migrations work, but some of them do work.
• run Python offers a way to rewind migrations and can fix issues with migrations.
• Code changes should be made after database updates, not before.
• Back up your database before making major updates.
• run Python doesn’t guarantee success, but failure is often informative.
• Django’s make migrations-merge command can help resolve conflicts between separate branches.
• run Python functions can be used to reconstruct columns based on backups.
• Django 1.7 to 1.8 and 1.8 to 1.9 are backwards compatible upgrades.
• Django’s run.py script can be used to manage migrations recursively.
• Django’s migrate recorder can be used to debug migrations without affecting the database.
• Django can be used for full CI deployments to staging.