update a single attribute on dirty ActiveRecords

update_single_attribute.rb

module ActiveRecord
  class Base
    # updates a single attribute on the record directly to the database using
    # ActiveRecord::Base.update_all
    def update_single_attribute(name, value)
      write_attribute(name, value)
      self.class.update_all({name => value}, {self.class.primary_key => read_attribute(self.class.primary_key)}, {:limit => 1})
    end
  end
end