Rails3

Using Postgres

Make sure you have pg gem installed (not the old "postgres" gem)

gem install pg

Making a new app

rails -d postgresql my_rails_app

Your database.yml file

  development:
   adapter: postgresql
   host: localhost
   port: 5432
   username: your_db_username
   password: your_db_password
   database: your_rails_project_development
   schema_search_path: public
   encoding: utf8
   template: template0

More info

Try this: http://wiki.rubyonrails.org/database-support/postgres