Updated check for offload in python (dataset_helper.py and
iterators.py).
Updated auto_offload test in test_map_offload.py.
Changed MapNode.offload type from bool->int in bindings.cc.
Changed manual offload flag from int->enum.
Update offload end of pipeline detection to be column-specific.
Updated check for offload in python (dataset_helper.py and
iterators.py).
Updated auto_offload test in test_map_offload.py.
Changed MapNode.offload type from bool->int in bindings.cc.
Changed manual offload flag from int->enum.