Choosing the model layer

Except in rare cases where you need the absolute maximum performance and are coding directly against the database driver, you will almost always want to use a model layer or other database abstraction layer in your application. Which model layer you choose can have significant performance effects on your application, as well as influence what other libraries you can use in your application.

For SQL database model layers in Ruby, there are only two libraries with significant popularity (that is, over one million downloads), Active Record and Sequel. Active Record is by far the most popular option, due to it being the default model layer for the most popular web framework, Ruby on Rails. Outside of usage in Ruby on Rails, Sequel is probably slightly more popular than Active Record, but there is still a lot of Active Record use outside of Ruby on Rails.

Due to Active Record's popularity, many more libraries integrate with Active Record than integrate...