How to: Database Tools
* [connection_pool](https://github.com/mperham/connection_pool) - Generic connection pooling for Ruby, that can be used with anything, e.g. Redis, Dalli, etc.
* [Database Cleaner](https://github.com/DatabaseCleaner/database_cleaner) - Database Cleaner is a set of strategies for cleaning your database in Ruby.
* [Database Consistency](https://github.com/djezzzl/database_consistency) - An easy way to check that application constraints and database constraints are in sync.
* [Foreigner](https://github.com/matthuhiggins/foreigner) - Adds foreign key helpers to migrations and correctly dumps foreign keys to schema.rb.
* [Large Hadron Migrator](https://github.com/soundcloud/lhm) - Online MySQL schema migrations without locking the table.
* [Lol DBA](https://github.com/plentz/lol_dba) - Scan your models and displays a list of columns that probably should be indexed.
* [Online Migrations](https://github.com/fatkodima/online_migrations) - Catch unsafe PostgreSQL migrations in development and run them easier in production.
* [Polo](https://github.com/IFTTT/polo) - Creates sample database snapshots to work with real world data in development.
* [PgHero](https://github.com/ankane/pghero) - Postgres insights made easy.
* [Rails DB](https://github.com/igorkasyanchuk/rails_db) - Database Viewer and SQL Query Runner.
* [Rein](https://github.com/nullobject/rein) - Database constraints made easy for ActiveRecord.
* [Scenic](https://github.com/thoughtbot/scenic) - Versioned database views for Rails.
* [SchemaPlus](https://github.com/SchemaPlus/schema_plus) - SchemaPlus provides a collection of enhancements and extensions to ActiveRecord
* [SecondBase](https://github.com/customink/secondbase) - Seamless second database integration for Rails. SecondBase provides support for Rails to manage dual databases by extending ActiveRecord tasks that create, migrate, and test your application.
* [Seedbank](https://github.com/james2m/seedbank) - Seedbank allows you to structure your Rails seed data instead of having it all dumped into one large file.
* [Seed dump](https://github.com/rroblak/seed_dump) - Rails 4 task to dump (parts) of your database to db/seeds.rb.
* [Seed Fu](https://github.com/mbleigh/seed-fu) - Advanced seed data handling for Rails.
* [Standby](https://github.com/kenn/standby) - Read from standby databases for ActiveRecord (formerly Slavery).
* [Strong Migrations](https://github.com/ankane/strong_migrations) - Catch unsafe migrations in development.
* [Upsert](https://github.com/seamusabshere/upsert) - Upsert on MySQL, PostgreSQL, and SQLite3. Transparently creates functions (UDF) for MySQL and PostgreSQL; on SQLite3, uses INSERT OR IGNORE.