anchor.diff:            sub_qrys      = []                  :: [integer()],
             receiver_pid                        :: pid(),
             result        = []                  :: rows_acc() | aggregate_acc() | group_by_acc(),
  -          run_sub_qs_fn = fun run_sub_qs_fn/1 :: fun(),
             qbuf_ref                            :: undefined | riak_kv_qry_buffers:qbuf_ref(),
             orig_qry                            :: undefined | ?SQL_SELECT{}
            }).
  
positive.code:                 InitialState
          end,
      SubQs = [{{qry, Q}, {qid, {I, QId}}} || {I, Q} <- ZQueries],
      ok = RunSubQs(SubQs),
      {ok, State#state{qid          = QId,
                       receiver_pid = ReceiverPid,
                       qry          = Qry1,
  
negative.code: 
  %%
  execute_query({query, ReceiverPid, QId, [Qry1|_] = SubQueries, _DDL, QBufRef},
                State) ->
      Indices = lists:seq(1, length(SubQueries)),
      ZQueries = lists:zip(Indices, SubQueries),
      %% all subqueries have the same select clause
  