mnesia_index_as_ets.erl

-module(mnesia_index_as_ets).

-export([main/0]).

-include_lib("eunit/include/eunit.hrl").
-record(kv, {key, value}).

main() ->
  mnesia:start(),
  
  mnesia:create_table(kv, [{attributes, record_info(fields, kv)},
                           {index, [#kv.value]}]),
  IndexEts = mnesia_lib:val({kv, {index, #kv.value}}),
  ?debugFmt("Index table of ets: ~p", [IndexEts]),
  ?debugFmt("Contents: ~p", [ets:tab2list(IndexEts)]),
  
  mnesia:activity(transaction, fun mnesia:write/1, [#kv{key=1, value="one"}]),
  mnesia:activity(transaction, fun mnesia:write/1, [#kv{key=2, value="two"}]),
  ?debugFmt("Contents: ~p", [ets:tab2list(IndexEts)]),
  
  mnesia:activity(transaction, fun mnesia:write/1, [#kv{key=3, value="three"}]),
  mnesia:activity(transaction, fun mnesia:write/1, [#kv{key=two, value="two"}]),
  ?debugFmt("Contents: ~p", [ets:tab2list(IndexEts)]),
  
  ?debugFmt("Table info: ~p", [ets:info(IndexEts)]),
  mnesia:stop(),
  ok.

Result of execution

19> mnesia_index_as_ets:main().

/mnesia/mnesia_index_as_ets.erl:14: Index table of ets: 200722

/mnesia/mnesia_index_as_ets.erl:15: Contents: []

/mnesia/mnesia_index_as_ets.erl:19: Contents: [{"one",1},{"two",2}]

/mnesia/mnesia_index_as_ets.erl:23: Contents: [{"one",1},{"three",3},{"two",2},{"two",two}]

/mnesia/mnesia_index_as_ets.erl:25: Table info: [{memory,390},

         {owner,<0.183.0>},

         {heir,none},

         {name,mnesia_index},

         {size,4},

         {node,nonode@nohost},

         {named_table,false},

         {type,bag},

         {keypos,1},

         {protection,public}]

ok

20>