Creating migrations in Supabase - Practice Exercises

Challenge - 5 Problems

❓ service_behavior

intermediate

What happens when you run supabase db push with no new migration files?

You have an existing Supabase project with migrations applied. You run the command supabase db push but have not added any new migration files. What is the expected behavior?

A The command detects no new migrations and makes no changes to the database schema.

B The command applies all existing migrations again, duplicating schema changes.

C The command deletes all existing tables and recreates them from scratch.

D The command throws an error indicating no migration files found.

💡 Hint

Think about what happens if there is nothing new to apply.

The supabase db push command only applies new migration files that have not yet been applied. If there are no new migrations, it does nothing and leaves the database schema unchanged.

❓ Configuration

intermediate

Which file must be updated to configure the database connection for Supabase migrations?

To run migrations with Supabase CLI, you need to specify the database connection details. Which configuration file is used to set the connection string for migrations?

A supabase/config.toml

B supabase/.dbconfig

C supabase/migrations.yaml

D .env

💡 Hint

Supabase uses environment variables for sensitive info.

The .env file holds environment variables including the database connection string used by Supabase CLI for migrations.

❓ Architecture

advanced

What is the best practice for organizing migration files in a Supabase project?

Consider a Supabase project with multiple developers working on database schema changes. How should migration files be organized to avoid conflicts and ensure smooth deployment?

A Each developer keeps migration files locally and runs them manually without sharing.

B Store all migration files in a single folder with timestamped filenames and commit them to version control.

C Use a single migration file for all changes and overwrite it for every update.

D Store migration files outside the project folder to avoid accidental commits.

💡 Hint

Think about collaboration and version control.

Best practice is to keep migration files in a dedicated folder with clear timestamps or version numbers, and commit them to version control so all developers share the same schema history.

❓ security

advanced

Which practice improves security when managing Supabase migration files?

When handling migration files that include sensitive schema changes, which practice helps protect sensitive information?

A Avoid including sensitive data like passwords or secrets directly in migration files.

B Store migration files in a public repository for transparency.

C Include database credentials inside migration SQL scripts for automation.

D Encrypt migration files before committing to version control.

💡 Hint

Think about what should never be in code files.

Migration files should never contain sensitive information such as passwords or secrets. These should be managed separately via environment variables or secret management tools.

🧠 Conceptual

expert

What is the effect of running supabase db reset in a project with existing migrations?

You run supabase db reset in your project directory. What happens to your database and migration files?

A Migration files are deleted but the database remains unchanged.

B Only the last migration is applied to the existing database without dropping it.

C The database is dropped and recreated, then all migrations are reapplied from the first to last.

D The command only clears the migration history without affecting the database schema.

💡 Hint

Consider what 'reset' usually means for a database.

The supabase db reset command drops the current database, recreates it fresh, and then reapplies all migration files in order to rebuild the schema from scratch.

Practice

1. What is the main purpose of creating migrations in Supabase?

easy

A. To save and track changes made to the database structure

B. To create user accounts automatically

C. To deploy frontend code to the server

D. To monitor server uptime and performance

Solution

1. Step 1: Understand what migrations do

   Migrations are files that record changes to the database schema over time.

2. Step 2: Identify the purpose in Supabase context

   Supabase uses migrations to save and track database structure changes so they can be applied consistently.

3. Final Answer:

   To save and track changes made to the database structure -> Option A

4. Quick Check:

   Migrations = track database changes [OK]

Hint: Migrations always track database structure changes [OK]

Common Mistakes:

• Confusing migrations with user management
• Thinking migrations deploy frontend code
• Assuming migrations monitor server health

2. Which command creates a new migration file in Supabase?

easy

A. supabase migration up

B. supabase db push

C. supabase migration new

D. supabase start migration

Solution

1. Step 1: Recall Supabase migration commands

   The command to create a new migration file is specifically designed to generate the file for changes.

2. Step 2: Match command to action

   supabase migration new creates a new migration file, while others apply or push changes.

3. Final Answer:

   supabase migration new -> Option C

4. Quick Check:

   Create migration file = supabase migration new [OK]

Hint: New migration files use 'migration new' command [OK]

Common Mistakes:

• Using 'db push' to create migration files
• Confusing 'migration up' with creation
• Typing incorrect commands like 'start migration'

3. After creating a migration file, which command applies the changes to your remote database?

medium

A. supabase migration up

B. supabase db push

C. supabase migration new

D. supabase db pull

Solution

1. Step 1: Understand commands for applying migrations

   supabase db push applies schema changes to the remote database by pushing local migrations.

2. Step 2: Differentiate commands

   supabase migration up applies migrations locally, while supabase db push pushes changes remotely.

3. Final Answer:

   supabase db push -> Option B

4. Quick Check:

   Apply remotely = db push [OK]

Hint: Use 'supabase db push' to apply migrations remotely [OK]

Common Mistakes:

• Using 'supabase migration up' to apply migrations remotely
• Confusing 'migration new' as apply command
• Thinking 'db pull' applies migrations

4. You ran supabase migration up but got an error saying migrations are missing. What is the likely cause?

medium

A. You used the wrong command to apply locally

B. You need to restart the Supabase server

C. Your database connection is offline

D. You forgot to create migration files before applying

Solution

1. Step 1: Analyze the error about missing migrations

   The error indicates no migration files exist to apply locally.

2. Step 2: Identify the cause

   This usually happens if migration files were never created with supabase migration new.

3. Final Answer:

   You forgot to create migration files before applying -> Option D

4. Quick Check:

   Missing migrations = no files created [OK]

Hint: Create migration files before applying locally [OK]

Common Mistakes:

• Assuming connection issues cause missing migrations
• Restarting server without creating files
• Confusing local and remote apply commands

5. You want to update your remote Supabase database with new schema changes. Which sequence of commands should you run?

hard

A. supabase migration new -> supabase start -> supabase migration up

B. supabase db push -> supabase migration new -> supabase migration up

C. supabase migration up -> supabase migration new -> supabase db push

D. supabase migration new -> supabase migration up -> supabase db push

Solution

1. Step 1: Create migration files first

   Use supabase migration new to save schema changes as migration files.

2. Step 2: Apply changes locally

   Run supabase start to update your local database with these changes.

3. Step 3: Apply migrations remotely

   Finally, run supabase migration up to update the remote database.

4. Final Answer:

   supabase migration new -> supabase start -> supabase migration up -> Option A

5. Quick Check:

   Create -> local start -> remote up [OK]

Hint: Create migration, start locally, then up remotely [OK]

Common Mistakes:

• Applying migrations before creating files
• Applying remotely before local test
• Mixing order of commands