Database setup for production in Ruby on Rails - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding Rails production database configuration

In a typical Rails app, where should you specify the production database credentials?

A In the config/database.yml file under the production section

B Directly in the config/environments/production.rb file

C Inside the Gemfile

D In the app/models/production.rb file

💡 Hint

Think about where Rails expects database connection details for different environments.

The config/database.yml file holds database settings for all environments, including production.

❓ component_behavior

intermediate

Effect of missing production database config

What happens if you try to run rails db:migrate RAILS_ENV=production but the production database is not configured properly?

A Rails raises a connection error and migration does not run

B Rails runs migrations on the development database instead

C Rails creates a new SQLite database automatically

D Rails skips migrations silently without error

💡 Hint

Consider what happens when Rails cannot connect to the specified database.

If the production database config is missing or incorrect, Rails cannot connect and raises an error.

📝 Syntax

advanced

Correct production database.yml snippet

Which of the following is the correct way to specify a PostgreSQL production database in config/database.yml?

A

production:
  adapter: postgresql
  encoding: utf8
  database: myapp_development
  pool: 5
  username: myuser
  password: mypass

B

production:
  adapter: mysql
  encoding: utf8
  database: myapp_production
  pool: 5
  username: myuser
  password: mypass

C

production:
  adapter: sqlite3
  database: db/production.sqlite3
  pool: 5

D

production:
  adapter: postgresql
  encoding: unicode
  database: myapp_production
  pool: 5
  username: myuser
  password: mypass

💡 Hint

PostgreSQL uses adapter: postgresql and production database name should match environment.

Option D correctly sets PostgreSQL adapter, encoding, and production database name.

🔧 Debug

advanced

Debugging production database connection error

You deployed your Rails app and get this error when accessing it: PG::ConnectionBad: could not connect to server: Connection refused. What is the most likely cause?

A The Rails secret key base is not set

B The Rails app is missing the 'pg' gem in the Gemfile

C PostgreSQL server is not running or not reachable from the app server

D The database.yml file has a syntax error in the development section

💡 Hint

Connection refused usually means the app cannot reach the database server.

This error means the PostgreSQL server is down or network connection is blocked.

❓ state_output

expert

Result of running migrations with multiple environments

Given this command run on a Rails app: RAILS_ENV=production rails db:migrate
Assuming the production database is configured and migrations exist, what is the state of the development database after this command?

A The development database is reset and migrated

B The development database remains unchanged; only the production database is migrated

C Both development and production databases are migrated

D The command fails because it tries to migrate both environments

💡 Hint

Consider how Rails handles environment variables for database commands.

Setting RAILS_ENV=production tells Rails to run migrations only on the production database.