Erlang QLC Joins - trying merge two tables but result data is duplicated

Questions / Help
, ,
1

Hi, someone have some Erlang qlc join examples? i’m trying merge two tables but result data is duplicated. i write this qlc:

disk_partitions() ->
  mnesia:transaction(
    fun() ->
      qlc:eval(
        qlc:q([
          {D0, D1, D2, D3, P, D5, D6} ||
            {D0, D1, D2, D3, _D4, D5, D6} <- mnesia:table(disk),
            P = {_P0, P1, _P2, _P3, _P4, _P5, _P6, _P7} <- mnesia:table(partition),
            D1 =:= re:replace(P1, "[0-9]+", "", [{return, binary}])
        ])
      )
    end
  ).

and returned this:

iex(43)> :join_queries.disk_partitions
{:atomic,
 [
   {:disk, "/dev/sdb", "101 GT", "dos",
    {:partition, "/dev/sdb1", [], "Test", true, "/some/fake/path", "fat32",
     "UU82-3O93"}, "AB87-3S21", "TOSHIBA"},
   {:disk, "/dev/sdb", "101 GT", "dos",
    {:partition, "/dev/sdb2", [], "2Record", false, "fake_point", "exfat",
     "som2_3de2"}, "AB87-3S21", "TOSHIBA"}
 ]}

i want some like this

{:atomic,
 [
   {:disk, "/dev/sdb", "101 GT", "dos",
    [{:partition, "/dev/sdb1", [], "Test", true, "/some/fake/path", "fat32",
     "UU82-3O93"}, {:partition, "/dev/sdb2", [], "2Record", false, "fake_point", "exfat", "som2_3de2"}] "AB87-3S21", "TOSHIBA"}
 ]}

when i tried adding {join, merge} i got the error:

iex(9)> :join_queries.disk_partitions
{:aborted,
 {:no_join_to_carry_out,
  [
    {:qlc, :check_join_option, [join: :merge], [file: 'qlc.erl', line: 2202]},
    {:qlc, :prep_join, 3, [file: 'qlc.erl', line: 2062]},
    {:qlc, :prepare_qlc, 7, [file: 'qlc.erl', line: 1672]},
    {:qlc, :eval, 2, [file: 'qlc.erl', line: 293]},
    {:mnesia_tm, :apply_fun, 3, [file: 'mnesia_tm.erl', line: 842]},
    {:mnesia_tm, :execute_transaction, 5, [file: 'mnesia_tm.erl', line: 818]},
    {:erl_eval, :do_apply, 6, [file: 'erl_eval.erl', line: 685]},
    {:elixir, :recur_eval, 3, [file: 'src/elixir.erl', line: 280]},
    {:elixir, :eval_forms, 3, [file: 'src/elixir.erl', line: 265]},
    {IEx.Evaluator, :handle_eval, 3, [file: 'lib/iex/evaluator.ex', line: 298]},
    {IEx.Evaluator, :do_eval, 3, [file: 'lib/iex/evaluator.ex', line: 274]},
    {IEx.Evaluator, :eval, 3, [file: 'lib/iex/evaluator.ex', line: 263]},
    {IEx.Evaluator, :loop, 1, [file: 'lib/iex/evaluator.ex', line: 157]},
    {IEx.Evaluator, :init, 4, [file: 'lib/iex/evaluator.ex', line: 32]},
    {:proc_lib, :init_p_do_apply, 3, [file: 'proc_lib.erl', line: 226]}
  ]}}

i readed erlang docs but idk how can i make to work the qlc joins.

Thanks.