# Multiverse :fire: Multiple databases for Rails One of the easiest ways to scale your database is to move large, infrequently-joined tables to a separate database. **ActiveRecord supports multiple databases, but Rails doesn’t provide a way to manage them.** Multiverse changes this. Works with Rails 4.2+ [![Build Status](https://travis-ci.org/ankane/multiverse.svg?branch=master)](https://travis-ci.org/ankane/multiverse) ## Installation Add this line to your application’s Gemfile: ```ruby gem 'multiverse' ``` ## Getting Started In this example, we’ll have a separate database for our e-commerce catalog that we’ll call `catalog`. The first step is to generate the necessary files. ```sh rails generate multiverse:db catalog ``` This creates a `CatalogRecord` class for models to inherit from and adds configuration to `config/database.yml`. It also creates a `db/catalog` directory for migrations and `schema.rb` to live. `rails` and `rake` commands run for the original database by default. To run commands for the new database, use the `DB` environment variable. For instance: Create the database ```sh DB=catalog rake db:create ``` Create a migration ```sh DB=catalog rails generate migration add_name_to_products ``` Run migrations ```sh DB=catalog rake db:migrate ``` Rollback ```sh DB=catalog rake db:rollback ``` ## Models Also works for models ```sh DB=catalog rails generate model Product ``` This generates ```rb class Product < CatalogRecord end ``` ## Web Servers For web servers that fork, be sure to reconnect after forking (just like you do with `ActiveRecord::Base`) ### Puma In `config/puma.rb`, add inside the `on_worker_boot` block ```ruby CatalogRecord.establish_connection :"catalog_#{Rails.env}" ``` ### Unicorn In `config/unicorn.rb`, add inside the `before_fork` block ```ruby CatalogRecord.connection.disconnect! ``` And inside the `after_fork` block ```ruby CatalogRecord.establish_connection :"catalog_#{Rails.env}" ``` ## Testing ### Fixtures [Rails fixtures](http://guides.rubyonrails.org/testing.html#the-low-down-on-fixtures) work automatically. ### Database Cleaner Database Cleaner supports multiple connections out of the box. ```ruby cleaner = DatabaseCleaner[:active_record, {model: CatalogRecord}] cleaner.strategy = :transaction cleaner.cleaning do # code end ``` [Read more here](https://github.com/DatabaseCleaner/database_cleaner#how-to-use-with-multiple-orms) ## History View the [changelog](https://github.com/ankane/multiverse/blob/master/CHANGELOG.md) ## Contributing Everyone is encouraged to help improve this project. Here are a few ways you can help: - [Report bugs](https://github.com/ankane/multiverse/issues) - Fix bugs and [submit pull requests](https://github.com/ankane/multiverse/pulls) - Write, clarify, or fix documentation - Suggest or add new features