In rails you have a lot great information in logs: db query time, view render time etc. But if you use mongoid 3+ you can see only query time for each requests but not for all db requests that been made in action. That is why i wrote this simple script:

module Moped module Instrumentation def self.instrument(klass) klass.class_eval do def logging(operations) instrument_start = (logger = Moped.logger) && logger.debug? && yield ensure instrument_end = 1000 * ( - instrument_start.to_f) MopedLogSubscriber.runtime += instrument_end log_operations(logger, operations, instrument_end) if instrument_start end end end class Railtie < Rails::Railtie initializer "moped.instrumentation" do |app| Moped::Instrumentation.instrument Moped::Node Moped::Instrumentation::MopedLogSubscriber.attach_to :action_controller end end class MopedLogSubscriber < ActiveSupport::LogSubscriber def self.runtime=(value) Thread.current["moped_rails_runtime"] = value end def self.runtime Thread.current["moped_rails_runtime"] ||= 0 end def self.reset_runtime! rt, self.runtime = runtime, 0 rt end def start_processing(event) MopedLogSubscriber.reset_runtime! end def process_action(event) runtime = ("Mongo: (%.4fms)" % MopedLogSubscriber.runtime) info(runtime) end def logger ActionController::Base.logger end end end end