Just about everytime I build a new Rails app I forget to use Postgres as my default database. The simple and straight forward way to start working with Postgres is to use the flag on your initial Rails build command rails new project-name --database=postgresql. Without the --database=postgresql, Rails will build your new app with Sqlite3 as the default databse.

First thing to do is change your Gemfile. Change the lines # Use sqlite3 as the database for Active Record gem 'sqlite3'

to

# Use postgres as the database for Active Record gem 'pg'

Run $bundle install after this to install the added gem.

Next /config/database.yaml needs to be changed. If you stared out with Sqlite3 the contents should look like this

SQLite. Versions 3.8.0 and up are supported.

gem install sqlite3

Ensure the SQLite 3 gem is defined in your Gemfile

gem ‘sqlite3’

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

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

Warning: The database defined as “test” will be erased and

re-generated from your development database when you run “rake”.

Do not set this db to the same as development or production.

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

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

This should be changed to `

PostgreSQL. Versions 8.2 and up are supported.

Install the pg driver:

gem install pg

On OS X with Homebrew:

gem install pg — —with-pg-config=/usr/local/bin/pg_config

On OS X with MacPorts:

gem install pg — —with-pg-config=/opt/local/lib/postgresql84/bin/pg_config

On Windows:

gem install pg

Choose the win32 build.

Install PostgreSQL and put its /bin directory on your path.

Configure Using Gemfile

gem ‘pg’

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

Connect on a TCP socket. Omitted by default since the client uses a

domain socket that doesn’t need configuration. Windows does not have

domain sockets, so uncomment these lines.

host: localhost

The TCP port the server listens on. Defaults to 5432.

If your server runs on a different port number, change accordingly.

port: 5432

Schema search path. The server defaults to $user,public

schemasearchpath: myapp,sharedapp,public

Minimum log levels, in increasing order:

debug5, debug4, debug3, debug2, debug1,

log, notice, warning, error, fatal, and panic

Defaults to warning.

min_messages: notice

Warning: The database defined as “test” will be erased and

re-generated from your development database when you run “rake”.

Do not set this db to the same as development or production.

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

`