gistfile1.rb

#you can now chain operations by scope

Order.scoped_by_customer_id(12)
Order.scoped_by_customer_id(12).find(:all,  :conditions => "status = 'open'") 
Order.scoped_by_customer_id(12).scoped_by_status("open") 

#Customer is a trillion row table
Customer.find_in_batches(:conditions => {:active => true}) do |customer_group| 
   customer_group.each { |customer| customer.update_account_balance! } 
end