Rolling back migrations in Supabase - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does 'rolling back migrations' mean in Supabase?

It means undoing changes made to the database schema by reversing the last migration or a set of migrations.

beginner

Which Supabase CLI command is used to roll back the last migration?

The command is supabase db migration down to undo the last migration specifically, or supabase db reset which resets the database including rolling back all migrations.

intermediate

Why should you be careful when rolling back migrations in Supabase?

Because rolling back can delete or alter data and schema, potentially causing data loss if not backed up or tested properly.

intermediate

What is a safe practice before rolling back migrations?

Always back up your database and test the rollback process in a development environment before applying it in production.

intermediate

How does Supabase track migrations to enable rolling back?

Supabase stores migration history in a special table that records applied migrations, allowing it to know which ones to undo.

Which command rolls back the last migration in Supabase?

A supabase db migrate apply

B supabase db migration down

C supabase db push

D supabase db reset --no-rollback

supabase db migration down reverses the last migration applied to the database.

What is a risk of rolling back migrations without backup?

A Increased storage space

B Faster database queries

C Data loss or corruption

D Automatic schema upgrade

Rolling back can remove schema changes and data, causing data loss if no backup exists.

Where does Supabase store migration history?

A In a special migrations table

B In the application code

C In the cloud storage bucket

D In the user session

Migration history is stored in a database table to track applied migrations.

What should you do before rolling back migrations in production?

A Back up the database

B Delete all data

C Restart the server

D Ignore warnings

Backing up ensures you can restore data if rollback causes issues.

Which command resets the database including rolling back all migrations?

A supabase db push

B supabase db migrate undo

C supabase db status

D supabase db reset

supabase db reset resets the database and rolls back all migrations.

Explain the process and risks of rolling back migrations in Supabase.

Think about what happens to your database schema and data when you reverse migrations.

Describe best practices to follow before and after rolling back migrations.

Consider safety steps to avoid data loss and ensure smooth rollback.

Practice

1. What does the command supabase db rollback do?

easy

A. It creates a new migration file.

B. It undoes the last applied database migration.

C. It applies all pending migrations to the database.

D. It deletes the entire database.

Solution

1. Step 1: Understand the purpose of rollback

   Rollback means undoing changes, so this command reverses migrations already applied.

2. Step 2: Identify the command effect

   supabase db rollback specifically undoes the last migration applied to the database.

3. Final Answer:

   It undoes the last applied database migration. -> Option B

4. Quick Check:

   Rollback = undo last migration [OK]

Hint: Rollback means undo last migration applied [OK]

Common Mistakes:

• Confusing rollback with applying migrations
• Thinking rollback creates new migrations
• Assuming rollback deletes the database

2. Which of the following is the correct syntax to rollback the last 3 migrations using Supabase CLI?

easy

A. supabase db rollback --steps 3

B. supabase db rollback -n 3

C. supabase rollback db 3

D. supabase db undo 3

Solution

1. Step 1: Recall the rollback command syntax

   The Supabase CLI uses --steps to specify how many migrations to rollback.

2. Step 2: Match the correct option

   supabase db rollback --steps 3 uses supabase db rollback --steps 3, which is the correct syntax.

3. Final Answer:

   supabase db rollback --steps 3 -> Option A

4. Quick Check:

   Use --steps to rollback multiple migrations [OK]

Hint: Use --steps to specify rollback count [OK]

Common Mistakes:

• Using incorrect flags like -n instead of --steps
• Wrong command order like 'rollback db'
• Using 'undo' instead of 'rollback'

3. Given the following commands run in order:
supabase db push
supabase db push
supabase db rollback --steps 1
What is the state of migrations after these commands?

medium

A. All migrations are rolled back except the last one.

B. No migrations are applied.

C. Both migrations are still applied.

D. Only the first migration is applied.

Solution

1. Step 1: Apply two migrations

   Running supabase db push twice applies two migrations in order.

2. Step 2: Rollback one migration

   The rollback with --steps 1 undoes the last applied migration, leaving the first migration applied.

3. Final Answer:

   Only the first migration is applied. -> Option D

4. Quick Check:

   Rollback 1 step removes last migration applied [OK]

Hint: Rollback with --steps 1 undoes last migration only [OK]

Common Mistakes:

• Assuming rollback removes all migrations
• Thinking rollback does not affect applied migrations
• Confusing push and rollback order

4. You run supabase db rollback --steps 2 but get an error saying no migrations to rollback. What is the most likely cause?

medium

A. There are fewer than 2 migrations applied to rollback.

B. The migrations folder is missing.

C. The database connection is not configured.

D. Rollback command requires a --force flag.

Solution

1. Step 1: Understand rollback error

   The error indicates no migrations to rollback, meaning none or fewer than requested are applied.

2. Step 2: Identify cause

   If fewer than 2 migrations are applied, trying to rollback 2 steps causes this error.

3. Final Answer:

   There are fewer than 2 migrations applied to rollback. -> Option A

4. Quick Check:

   Rollback steps > applied migrations causes error [OK]

Hint: Check applied migrations count before rollback steps [OK]

Common Mistakes:

• Assuming rollback always works without applied migrations
• Thinking rollback needs --force flag
• Ignoring database connection issues

5. You have applied 5 migrations but want to rollback only the 3rd migration without affecting others. Which approach is best?

hard

A. Delete the 3rd migration file and run supabase db push.

B. Use supabase db rollback --steps 3 to rollback only the 3rd migration.

C. Rollback all migrations from the 3rd onwards, then reapply the ones after it.

D. Directly edit the database to remove changes from the 3rd migration.

Solution

1. Step 1: Understand migration order

   Migrations apply in order; you cannot rollback a middle migration without undoing later ones first.

2. Step 2: Plan rollback and reapply

   Rollback migrations after the 3rd (steps 2), then rollback the 3rd, then reapply the later migrations.

3. Final Answer:

   Rollback all migrations from the 3rd onwards, then reapply the ones after it. -> Option C

4. Quick Check:

   Rollback middle migration requires undoing later ones first [OK]

Hint: Undo later migrations first, then rollback target migration [OK]

Common Mistakes:

• Trying to rollback a single middle migration directly
• Deleting migration files without rollback
• Editing database manually causing inconsistency