PostgreSQL + Rails citext

Rails 4.2+

Rails 4.2 has native support for the citext column type.

Rails < 4.2

If you're using Rails < 4.2, you can try using the activerecord-postgresql-citext gem.

This allows you to write migrations like this:

def up
  enable_extension("citext")                   

  create_table :models, :force => true do |t|  
    t.citext :name                             
    t.timestamps                               
  end                                          
end