def _parse_commit_response(commit_response_pb):
    """Extract response data from a commit response.

    :type commit_response_pb: :class:`._generated.datastore_pb2.CommitResponse`
    :param commit_response_pb: The protobuf response from a commit request.

    :rtype: tuple
    :returns': The pair of the number of index updates and a list of
               :class:`._generated.entity_pb2.Key` for each incomplete key
               that was completed in the commit.
    """
    mut_result = commit_response_pb.mutation_result
    index_updates = mut_result.index_updates
    completed_keys = list(mut_result.insert_auto_id_key)
    return index_updates, completed_keys