anchor.diff:  handle_message({meta, Meta0}, {Worker, From}, State) ->
       Tot = couch_util:get_value(total, Meta0, 0),
       Off = couch_util:get_value(offset, Meta0, 0),
  +    Seq = couch_util:get_value(update_seq, Meta0, 0),
       #collector{
           callback = Callback,
           counters = Counters0,
           total_rows = Total0,
           offset = Offset0,
  -        user_acc = AccIn
  +        user_acc = AccIn,
  +        update_seq = UpdateSeq0
       } = State,
       % Assert that we don't have other messages from this
       % worker when the total_and_offset message arrives.
  
positive.code:     Counters1 = fabric_dict:update_counter(Worker, 1, Counters0),
      Total = Total0 + Tot,
      Offset = Offset0 + Off,
      case fabric_dict:any(0, Counters1) of
      true ->
          {ok, State#collector{
              counters = Counters1,
              total_rows = Total,
              offset = Offset
          }};
      false ->
          FinalOffset = erlang:min(Total, Offset+State#collector.skip),
          Meta = [{total, Total}, {offset, FinalOffset}],
          {Go, Acc} = Callback({meta, Meta}, AccIn),
          {Go, State#collector{
              counters = fabric_dict:decrement_all(Counters1),
              total_rows = Total,
              offset = FinalOffset,
              user_acc = Acc
          }}
      end;
  
  
negative.code:     end.
  
  go(DbName, _Options, Workers, QueryArgs, Callback, Acc0) ->
      #mrargs{limit = Limit, skip = Skip, update_seq = UpdateSeq} = QueryArgs,
      State = #collector{
          db_name = DbName,
          query_args = QueryArgs,
  