anchor.diff:                     num_of_rack_replicas = Level2,
                      max_mdc_targets = ?DEF_MAX_MDC_TARGETS
                     }.
  +
  +
  +%% @private
  +transform_1() ->
  +    Table = ?TBL_CLUSTER_INFO,
  +    case catch mnesia:ets(fun ets:first/1, [Table]) of
  +        {'EXIT', Cause} ->
  +            {error, Cause};
  +        '$end_of_table' ->
  +            ok;
  +        Key ->
  +            case transform_2(Key) of
  +                ok ->
  +                    transform_1(Key);
  +                _Error ->
  +                    ok
  +            end
  +    end.
  +transform_1(PrevKey) ->
  +    Table = ?TBL_CLUSTER_INFO,
  +    case catch mnesia:ets(fun ets:next/2, [Table, PrevKey]) of
  +        {'EXIT', Cause} ->
  +            {error, Cause};
  +        '$end_of_table' ->
  +            ok;
  +        Key ->
  +            case transform_2(Key) of
  +                ok ->
  +                    transform_1(Key);
  +                _Error ->
  +                    ok
  +            end
  +    end.
  +
  +%% @private
  +transform_2(Key) ->
  +    case ?MODULE:get(Key) of
  +        {ok, #?CLUSTER_INFO{cluster_id = ClusterId,
  +                            dc_id = DCId} = ClusterInfo} ->
  +            ClusterId_1 = case is_atom(ClusterId) of
  +                              true  -> ClusterId;
  +                              false -> list_to_atom(ClusterId)
  +                          end,
  +            DCId_1 = case is_atom(DCId) of
  +                         true  -> DCId;
  +                         false -> list_to_atom(DCId)
  +                     end,
  +            ?MODULE:delete(ClusterId),
  +            ?MODULE:update(ClusterInfo#?CLUSTER_INFO{cluster_id = ClusterId_1,
  +                                                     dc_id = DCId_1}),
  +            ok;
  +        _ ->
  +            void
  +    end.
  
positive.code: find_by_limit(Rows, Acc) when Rows == length(Acc) ->
      {ok, Acc};
  find_by_limit(Rows, []) ->
      Table =  ?TBL_CLUSTER_INFO,
      case catch mnesia:ets(fun ets:first/1, [Table]) of
          {'EXIT', Cause} ->
              {error, Cause};
  
negative.code: find_by_limit(Rows,_ClusterId, Acc) when Rows == length(Acc) ->
      {ok, Acc};
  find_by_limit(Rows, ClusterId, Acc) ->
      Table = ?TBL_CLUSTER_INFO,
      case catch mnesia:ets(fun ets:next/2, [Table, ClusterId]) of
          {'EXIT', Cause} ->
              {error, Cause};
  