Rails6: Switching SQlite3 to Postgres

A rails app uses SQlite3 as a built-in database.

The following command will create a new rails project with SQlite3:

rails new project

If you want to change the databasePostgres, DB2, MYSQL, and SQL Server, replace dbname with your selected db in the command below:

rails new project -d dbname

Switch SQlite3 to Postgres

1. Install Postgresql (if not already installed in the project directory):

gem install pg

2. Update Gemfile:

cd Project
nano Gemfile

Replace the following line:

gem 'sqlite3'

With:

gem 'pg'

Once all changes are made, run bundle install to update the Gemfile.lock file.

3. Update the database.yml file

The databse.yml file has the following commands:

default: &default
  adapter: sqlite3
  pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>
  timeout: 5000

development:
  <<: *default
  database: db/development.sqlite3

test:
  <<: *default
  database: db/test.sqlite3

production:
  <<: *default
  database: db/production.sqlite3

4. Remove all the above lines from the database.yml.

• set postgresql as adapter

• set unicode as encoding

• set your application name as database name

• set pool = 5

The final development version will be:

development:
  adapter: postgresql
  encoding: unicode
  database: yourApp_development
  pool: 5
  username: username
  password:
  timeout: 5000

Then, repeat all the steps for test:

test:
adapter: postgresql
encoding: unicode
database: youApp_test
pool: 5
username: username
password:
timeout: 5000

5. After making all changes, run the following commands:

rake db:setup
...
...some messages...
...
rake db:migrate

Try all the above commands, one by one, in the terminal below: