README.md

Commands examples

If the namespace is not used then the commands will perform on top of the default database.

  bundle exec rake db:create
  bundle exec rake db:migrate 

By using the namespace we are going to use all the configuration for our alternate DB.

  bundle exec rake pg:db:create
  bundle exec rake pg:db:migrate 

Notes

• From here having a more complex structure with more than one alternative database should be easy.

More resources

More info: http://stackoverflow.com/questions/1635885/rails-mysql-postgres-at-the-same-time-in-the-same-app

base.rb

# Public: Provide a base class for accessing the store database.
# All models inheriting from this class will use by default the data store DB.
class PostgresRecord::Base < ActiveRecord::Base
  DATABASE_CONFIG_FILE = Rails.root.join('config/database.pg.yml')

  # Tell Active Record (AR) to not look up for a table called like this class,
  # since this class is only used to add custom config for AR
  self.abstract_class = true

  databases = YAML::load(File.read(DATABASE_CONFIG_FILE))
  establish_connection(databases[Rails.env])
end

database.pg.yml

common: &common
  adapter: postgresql
  encoding: unicode
  pool: 5
  timeout: 5000
  min_messages: warning

development:
  <<: *common
  database: administrator_development

test:
  <<: *common
  database: administrator_test

production:
  <<: *common
  database: administrator_production

database.yml

# config/database.yml

development: &development
  adapter: sqlite3
  database: db/administrator_development.sqlite3
  pool: 5
  timeout: 5000

test:
  adapter: sqlite3
  database: db/administrator_test.sqlite3
  pool: 5
  timeout: 5000

pg.rake

namespace :pg do
  desc "Configure the variables that rails need in order to look up for the db configuration in a different folder"
  task :set_custom_db_config_paths do
    ENV["SCHEMA"] = "db_pg/schema.rb"
    Rails.application.config.paths["db"] = ["db_pg/pg"]
    Rails.application.config.paths["db/migrate"] = ["db_pg/migrate"]
    Rails.application.config.paths["db/seeds"] = ["db_pg/seeds.rb"]
    Rails.application.config.paths["config/database"] = ["config/database.pg.yml"]
  end

  namespace :db do
    namespace :test do
      task prepare: :set_custom_db_config_paths do
        Rake::Task["db:test:prepare"].invoke
      end
    end

    task drop: :set_custom_db_config_paths do
      Rake::Task["db:drop"].invoke
    end

    task create: :set_custom_db_config_paths do
      Rake::Task["db:create"].invoke
    end

    task migrate: :set_custom_db_config_paths do
      Rake::Task["db:migrate"].invoke
    end

    task rollback: :set_custom_db_config_paths do
      Rake::Task["db:rollback"].invoke
    end

    task seed: :set_custom_db_config_paths do
      Rake::Task["db:seed"].invoke
    end

    task version: :set_custom_db_config_paths do
      Rake::Task["db:version"].invoke
    end
  end
end