Database migration in production in Django - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a database migration in Django?

A database migration in Django is a way to update the database schema to match changes in your models. It helps keep the database structure in sync with your code without losing data.

beginner

Why should you be careful when running migrations in production?

Because migrations can change the database structure, running them in production can cause downtime or data loss if not done carefully. It's important to plan and test migrations to avoid breaking the live app.

beginner

What command do you use to create migrations in Django?

You use python manage.py makemigrations to create migration files based on model changes.

beginner

How do you apply migrations to the production database?

You run python manage.py migrate on the production server to apply all pending migrations safely.

intermediate

What is a common strategy to avoid downtime during production migrations?

A common strategy is to use zero-downtime deployment techniques, like running migrations in steps, using database locks carefully, or applying non-blocking migrations during low traffic times.

Which Django command creates migration files after model changes?

A python manage.py makemigrations

B python manage.py migrate

C python manage.py runserver

D python manage.py collectstatic

The command makemigrations creates migration files based on model changes.

What does python manage.py migrate do?

A Creates migration files

B Applies migrations to the database

C Starts the Django server

D Deletes old migrations

The migrate command applies all pending migrations to the database.

Why is it important to test migrations before running them in production?

A To avoid syntax errors in Python code

B To speed up the server

C To update Django version

D To prevent downtime or data loss

Testing migrations helps prevent downtime or data loss in the live environment.

Which of these is a good practice for production migrations?

A Backup the database before migrating

B Ignore migration errors

C Run migrations during peak traffic

D Skip migrations to save time

Backing up the database before migrating protects data if something goes wrong.

What can cause downtime during a migration?

A Running migrations on a test server

B Using <code>makemigrations</code> command

C Adding new fields without default values

D Writing model comments

Adding new fields without defaults can lock tables and cause downtime.

Explain the steps to safely perform a database migration in a Django production environment.

Think about preparation, testing, backup, and applying changes carefully.

Describe common challenges you might face when running migrations in production and how to handle them.

Consider risks and strategies to minimize impact.