Execution example::

  reference_acquire --target_name Users --recursive dependent
  # [[0, 1337566253.89858, 0.000355720520019531], true]
  # select Users ...
  # load --table Users ...
  reference_release --target_name Users --recursive dependent
  # [[0, 1337566253.89858, 0.000355720520019531], true]
