mnesia_ext: Dumper and schema changes

2 files changed, 689 insertions, 170 deletions

diff --git a/lib/mnesia/src/mnesia_dumper.erl b/lib/mnesia/src/mnesia_dumper.erl
index 0e954d869d..845ad0ac39 100644
--- a/lib/mnesia/src/mnesia_dumper.erl
+++ b/lib/mnesia/src/mnesia_dumper.erl
@@ -38,6 +38,8 @@
          needs_dump_ets/1,
 	 raw_dump_table/2,
 	 raw_named_dump_table/2,
+	 dump_to_logfile/2,
+	 load_from_logfile/3,
 	 start_regulator/0,
 	 opt_dump_log/1,
 	 update/3,
@@ -271,15 +273,25 @@ do_insert_rec(Tid, Rec, InPlace, InitBy, LogV) ->
 	    end
     end,
     D = Rec#commit.disc_copies,
+    ExtOps = commit_ext(Rec),
     insert_ops(Tid, disc_copies, D, InPlace, InitBy, LogV),
+    [insert_ops(Tid, Ext, Ops, InPlace, InitBy, LogV) ||
+	{Ext, Ops} <- ExtOps,
+	storage_semantics(Ext) == disc_copies],
     case InitBy of
 	startup ->
 	    DO = Rec#commit.disc_only_copies,
-	    insert_ops(Tid, disc_only_copies, DO, InPlace, InitBy, LogV);
+	    insert_ops(Tid, disc_only_copies, DO, InPlace, InitBy, LogV),
+	    [insert_ops(Tid, Ext, Ops, InPlace, InitBy, LogV) ||
+		{Ext, Ops} <- ExtOps, storage_semantics(Ext) == disc_only_copies];
 	_ ->
 	    ignore
     end.
 
+commit_ext(#commit{external_copies = C}) ->
+    lists:foldl(fun({Ext, Op}, D) ->
+			orddict:append(Ext, Op, D)
+		end, orddict:new(), C).
 
 update(_Tid, [], _DumperMode) ->
     dumped;
@@ -330,14 +342,15 @@ insert_ops(Tid, Storage, [Op | Ops], InPlace, InitBy, Ver) when Ver < "4.3" ->
 %% Normal ops
 
 disc_insert(_Tid, Storage, Tab, Key, Val, Op, InPlace, InitBy) ->
-    case open_files(Tab, Storage, InPlace, InitBy) of
+    Semantics = storage_semantics(Storage),
+    case open_files(Tab, Semantics, Storage, InPlace, InitBy) of
 	true ->
-	    case Storage of
+	    case Semantics of
 		disc_copies when Tab /= schema ->
 		    mnesia_log:append({?MODULE,Tab}, {{Tab, Key}, Val, Op}),
 		    ok;
 		_ ->
-		    dets_insert(Op,Tab,Key,Val)
+		    dets_insert(Op,Tab,Key,Val,Storage)
 	    end;
 	false ->
 	    ignore
@@ -349,34 +362,37 @@ disc_insert(_Tid, Storage, Tab, Key, Val, Op, InPlace, InitBy) ->
 %% Otherwise we will get a double increment.
 %% This is perfect but update_counter is a dirty op.
 
-dets_insert(Op,Tab,Key,Val) ->
+dets_insert(Op,Tab,Key,Val, Storage0) ->
+    Storage = if Tab == schema -> disc_only_copies;
+		 true -> Storage0
+	      end,
     case Op of
 	write ->
 	    dets_updated(Tab,Key),
-	    ok = dets:insert(Tab, Val);
+	    ok = mnesia_lib:db_put(Storage, Tab, Val);
 	delete ->
 	    dets_updated(Tab,Key),
-	    ok = dets:delete(Tab, Key);
+	    ok = mnesia_lib:db_erase(Storage, Tab, Key);
 	update_counter ->
 	    case dets_incr_counter(Tab,Key) of
 		true ->
 		    {RecName, Incr} = Val,
-		    try _ = dets:update_counter(Tab, Key, Incr)
+		    try _ = mnesia_lib:db_update_counter(Storage, Tab, Key, Incr)
 		    catch error:_ when Incr < 0 ->
 			    Zero = {RecName, Key, 0},
-			    ok = dets:insert(Tab, Zero);
+			    ok = mnesia_lib:db_put(Storage, Tab, Zero);
 			  error:_ ->
 			    Init = {RecName, Key, Incr},
-			    ok = dets:insert(Tab, Init)
+			    ok = mnesia_lib:db_put(Storage, Tab, Init)
 		    end;
 		false ->  ok
 	    end;
 	delete_object ->
 	    dets_updated(Tab,Key),
-	    ok = dets:delete_object(Tab, Val);
+	    mnesia_lib:db_match_erase(Storage, Tab, Val);
 	clear_table ->
 	    dets_cleared(Tab),
-	    ok = dets:delete_all_objects(Tab)
+	    ok = mnesia_lib:db_match_erase(Storage, Tab, '_')
     end.
 
 dets_updated(Tab,Key) ->
@@ -431,23 +447,29 @@ insert(_Tid, _Storage, _Tab, _Key, [], _Op, _InPlace, _InitBy) ->
     ok;
 
 insert(Tid, Storage, Tab, Key, Val, Op, InPlace, InitBy) ->
+    Semantics = storage_semantics(Storage),
     Item = {{Tab, Key}, Val, Op},
     case InitBy of
 	startup ->
 	    disc_insert(Tid, Storage, Tab, Key, Val, Op, InPlace, InitBy);
 
-	_ when Storage == ram_copies ->
+	_ when Semantics == ram_copies ->
 	    mnesia_tm:do_update_op(Tid, Storage, Item),
 	    Snmp = mnesia_tm:prepare_snmp(Tab, Key, [Item]),
 	    mnesia_tm:do_snmp(Tid, Snmp);
 
-	_ when Storage == disc_copies ->
+	_ when Semantics == disc_copies ->
 	    disc_insert(Tid, Storage, Tab, Key, Val, Op, InPlace, InitBy),
 	    mnesia_tm:do_update_op(Tid, Storage, Item),
 	    Snmp = mnesia_tm:prepare_snmp(Tab, Key, [Item]),
 	    mnesia_tm:do_snmp(Tid, Snmp);
 
-	_ when Storage == disc_only_copies ->
+	_ when Semantics == disc_only_copies ->
+	    mnesia_tm:do_update_op(Tid, Storage, Item),
+	    Snmp = mnesia_tm:prepare_snmp(Tab, Key, [Item]),
+	    mnesia_tm:do_snmp(Tid, Snmp);
+
+	_ when element(1, Storage) == ext ->
 	    mnesia_tm:do_update_op(Tid, Storage, Item),
 	    Snmp = mnesia_tm:prepare_snmp(Tab, Key, [Item]),
 	    mnesia_tm:do_snmp(Tid, Snmp);
@@ -456,6 +478,9 @@ insert(Tid, Storage, Tab, Key, Val, Op, InPlace, InitBy) ->
 	    ignore
     end.
 
+disc_delete_table(Tab, {ext, Alias, Mod}) ->
+    Mod:close_table(Alias, Tab),
+    Mod:delete_table(Alias, Tab);
 disc_delete_table(Tab, Storage) ->
     case mnesia_monitor:use_dir() of
 	true ->
@@ -485,11 +510,14 @@ disc_delete_table(Tab, Storage) ->
 	    ok
     end.
 
-disc_delete_indecies(_Tab, _Cs, Storage) when Storage /= disc_only_copies ->
-    ok;
-disc_delete_indecies(Tab, Cs, disc_only_copies) ->
-    Indecies = Cs#cstruct.index,
-    mnesia_index:del_transient(Tab, Indecies, disc_only_copies).
+disc_delete_indecies(Tab, Cs, Storage) ->
+    case storage_semantics(Storage) of
+	disc_only_copies ->
+	    Indecies = Cs#cstruct.index,
+	    mnesia_index:del_transient(Tab, Indecies, Storage);
+	_ ->
+	    ok
+    end.
 
 insert_op(Tid, Storage, {{Tab, Key}, Val, Op}, InPlace, InitBy) ->
     %% Propagate to disc only
@@ -515,6 +543,8 @@ insert_op(Tid, _, {op, change_table_copy_type, N, FromS, ToS, TabDef}, InPlace,
     Cs = mnesia_schema:list2cs(TabDef),
     Val = mnesia_schema:insert_cstruct(Tid, Cs, true), % Update ram only
     {schema, Tab, _} = Val,
+    FromSem = storage_semantics(FromS),
+    ToSem = storage_semantics(ToS),
     case lists:member(N, val({current, db_nodes})) of
 	true when InitBy /= startup  ->
 	    mnesia_controller:add_active_replica(Tab, N, Cs);
@@ -527,62 +557,118 @@ insert_op(Tid, _, {op, change_table_copy_type, N, FromS, ToS, TabDef}, InPlace,
 	    Dat  = mnesia_lib:tab2dat(Tab),
 	    Dcd  = mnesia_lib:tab2dcd(Tab),
 	    Dcl  = mnesia_lib:tab2dcl(Tab),
+	    Logtmp  = mnesia_lib:tab2logtmp(Tab),
 	    case {FromS, ToS} of
-		{ram_copies, disc_copies} when Tab == schema ->
-		    ok = ensure_rename(Dmp, Dat);
-		{ram_copies, disc_copies} ->
-		    file:delete(Dcl),
-		    ok = ensure_rename(Dmp, Dcd);
-		{disc_copies, ram_copies} when Tab == schema ->
-		    mnesia_lib:set(use_dir, false),
-		    mnesia_monitor:unsafe_close_dets(Tab),
-		    ok = file:delete(Dat);
-		{disc_copies, ram_copies} ->
-		    _ = file:delete(Dcl),
-		    _ = file:delete(Dcd),
-		    ok;
-		{ram_copies, disc_only_copies} ->
-		    ok = ensure_rename(Dmp, Dat),
-		    true = open_files(Tab, disc_only_copies, InPlace, InitBy),
-		    %% ram_delete_table must be done before init_indecies,
-		    %% it uses info which is reset in init_indecies,
-		    %% it doesn't matter, because init_indecies don't use
-		    %% the ram replica of the table when creating the disc
-		    %% index; Could be improved :)
-		    mnesia_schema:ram_delete_table(Tab, FromS),
-		    PosList = Cs#cstruct.index,
-		    mnesia_index:init_indecies(Tab, disc_only_copies, PosList);
-		{disc_only_copies, ram_copies} ->
-		    mnesia_monitor:unsafe_close_dets(Tab),
-		    disc_delete_indecies(Tab, Cs, disc_only_copies),
-		    case InitBy of
-			startup ->
-			    ignore;
+		{{ext,_FromAlias,_FromMod},{ext,ToAlias,ToMod}} ->
+		    disc_delete_table(Tab, FromS),
+                    ok = ToMod:delete_table(ToAlias, Tab),
+		    ok = ToMod:create_table(ToAlias, Tab, []),
+		    ok = ToMod:load_table(ToAlias, Tab, {dumper,change_table_copy_type}, TabDef),
+		    ok = load_from_logfile(ToS, Tab, Logtmp),
+		    file:delete(Logtmp),
+		    restore_indexes(Tab, ToS, Cs);
+
+		{_,{ext,ToAlias,ToMod}} ->
+		    case FromSem of
+			ram_copies ->
+			    mnesia_schema:ram_delete_table(Tab, FromS);
 			_ ->
-			    mnesia_controller:get_disc_copy(Tab),
-			    ok
+			    if FromSem == disc_copies ->
+				    mnesia_schema:ram_delete_table(
+				      Tab, FromS);
+			       true -> ok
+			    end,
+			    disc_delete_table(Tab, FromS)
 		    end,
-		    disc_delete_table(Tab, disc_only_copies);
-		{disc_copies, disc_only_copies} ->
-		    ok = ensure_rename(Dmp, Dat),
-		    true = open_files(Tab, disc_only_copies, InPlace, InitBy),
-		    mnesia_schema:ram_delete_table(Tab, FromS),
-		    PosList = Cs#cstruct.index,
-		    mnesia_index:init_indecies(Tab, disc_only_copies, PosList),
-		    _ = file:delete(Dcl),
-		    _ = file:delete(Dcd),
-		    ok;
-		{disc_only_copies, disc_copies} ->
-		    mnesia_monitor:unsafe_close_dets(Tab),
-		    disc_delete_indecies(Tab, Cs, disc_only_copies),
-		    case InitBy of
-			startup ->
-			    ignore;
-			_ ->
-			    mnesia_log:ets2dcd(Tab),
-			    mnesia_controller:get_disc_copy(Tab),
-			    disc_delete_table(Tab, disc_only_copies)
-		    end
+
+                    ok = ToMod:delete_table(ToAlias, Tab),
+		    ok = ToMod:create_table(ToAlias, Tab, []),
+		    ok = ToMod:load_table(ToAlias, Tab, {dumper,change_table_copy_type}, TabDef),
+		    ok = load_from_logfile(ToS, Tab, Logtmp),
+		    file:delete(Logtmp),
+		    restore_indexes(Tab, ToS, Cs);
+
+		{{ext,_FromAlias,_FromMod} = FromS, ToS} ->
+		    disc_delete_table(Tab, FromS),
+		    case ToS of
+			ram_copies ->
+			    change_disc_to_ram(
+			      Tab, Cs, FromS, ToS, Logtmp, InitBy);
+			disc_copies ->
+			    Args = [{keypos, 2}, public, named_table,
+				    Cs#cstruct.type],
+			    mnesia_monitor:mktab(Tab, Args),
+			    ok = load_from_logfile(ToS, Tab, Logtmp),
+			    file:delete(Logtmp);
+			disc_only_copies ->
+			    %% ok = ensure_rename(Dmp, Dat),
+			    true = open_files(Tab, ToS, InPlace, InitBy),
+			    ok = load_from_logfile(ToS, Tab, Logtmp),
+			    file:delete(Logtmp)
+		    end,
+		    restore_indexes(Tab, ToS, Cs);
+
+		_NoneAreExt ->
+
+                    case {FromSem, ToSem} of
+                        {ram_copies, disc_copies} when Tab == schema ->
+                            ok = ensure_rename(Dmp, Dat);
+                        {ram_copies, disc_copies} ->
+                            file:delete(Dcl),
+                            ok = ensure_rename(Dmp, Dcd);
+                        {disc_copies, ram_copies} when Tab == schema ->
+                            mnesia_lib:set(use_dir, false),
+                            mnesia_monitor:unsafe_close_dets(Tab),
+                            ok = file:delete(Dat);
+                        {disc_copies, ram_copies} ->
+                            _ = file:delete(Dcl),
+                            _ = file:delete(Dcd),
+                            ok;
+                        {ram_copies, disc_only_copies} ->
+                            ok = ensure_rename(Dmp, Dat),
+                            true = open_files(Tab, ToS, InPlace, InitBy),
+                            %% ram_delete_table must be done before
+                            %% init_indecies, it uses info which is reset
+                            %% in init_indecies, it doesn't matter, because
+                            %% init_indecies don't use the ram replica of
+                            %% the table when creating the disc index;
+                            %% Could be improved :)
+                            mnesia_schema:ram_delete_table(Tab, FromS),
+			    restore_indexes(Tab, ToS, Cs);
+                        {disc_only_copies, ram_copies} when FromS == disc_only_copies ->
+                            mnesia_monitor:unsafe_close_dets(Tab),
+                            disc_delete_indecies(Tab, Cs, FromS),
+                            case InitBy of
+                                startup ->
+                                    ignore;
+                                _ ->
+                                    mnesia_controller:get_disc_copy(Tab),
+                                    ok
+                            end,
+                            disc_delete_table(Tab, FromS);
+                        {disc_only_copies, ram_copies} when element(1, FromS) == ext ->
+			    change_disc_to_ram(
+			      Tab, Cs, FromS, ToS, Logtmp, InitBy);
+                        {disc_copies, disc_only_copies} ->
+                            ok = ensure_rename(Dmp, Dat),
+                            true = open_files(Tab, ToS, InPlace, InitBy),
+                            mnesia_schema:ram_delete_table(Tab, FromS),
+			    restore_indexes(Tab, ToS, Cs),
+			    _ = file:delete(Dcl),
+                            _ = file:delete(Dcd),
+                            ok;
+                        {disc_only_copies, disc_copies} ->
+                            mnesia_monitor:unsafe_close_dets(Tab),
+                            disc_delete_indecies(Tab, Cs, disc_only_copies),
+                            case InitBy of
+                                startup ->
+                                    ignore;
+                                _ ->
+                                    mnesia_log:ets2dcd(Tab),
+                                    mnesia_controller:get_disc_copy(Tab),
+                                    disc_delete_table(Tab, disc_only_copies)
+                            end
+                    end
 	    end;
 	true ->
 	    ignore
@@ -607,6 +693,9 @@ insert_op(Tid, _, {op, restore_recreate, TabDef}, InPlace, InitBy) ->
     Tab = Cs#cstruct.name,
     Type = Cs#cstruct.type,
     Storage = mnesia_lib:cs_to_storage_type(node(), Cs),
+    Semantics = if Storage==unknown -> unknown;
+		   true -> storage_semantics(Storage)
+		end,
     %% Delete all possibly existing files and tables
     disc_delete_table(Tab, Storage),
     disc_delete_indecies(Tab, Cs, Storage),
@@ -625,13 +714,13 @@ insert_op(Tid, _, {op, restore_recreate, TabDef}, InPlace, InitBy) ->
     
     %% And create new ones..
     if
-	(InitBy == startup) or (Storage == unknown) ->
+	(InitBy == startup) or (Semantics == unknown) ->
 	    ignore;
-	Storage == ram_copies ->
+	Semantics == ram_copies ->
 	    EtsProps = proplists:get_value(ets, StorageProps, []),
 	    Args = [{keypos, 2}, public, named_table, Type | EtsProps],
 	    mnesia_monitor:mktab(Tab, Args);
-	Storage == disc_copies ->
+	Semantics == disc_copies ->
 	    EtsProps = proplists:get_value(ets, StorageProps, []),
 	    Args = [{keypos, 2}, public, named_table, Type | EtsProps],
 	    mnesia_monitor:mktab(Tab, Args),
@@ -640,7 +729,7 @@ insert_op(Tid, _, {op, restore_recreate, TabDef}, InPlace, InitBy) ->
 		    {repair, false}, {mode, read_write}],
 	    {ok, Log} = mnesia_monitor:open_log(FArg),
 	    mnesia_monitor:unsafe_close_log(Log);
-	Storage == disc_only_copies ->
+	Storage == disc_only_copies ->  % note: Storage, not Semantics
 	    File = mnesia_lib:tab2dat(Tab),
 	    file:delete(File),
 	    DetsProps = proplists:get_value(dets, StorageProps, []),
@@ -649,7 +738,10 @@ insert_op(Tid, _, {op, restore_recreate, TabDef}, InPlace, InitBy) ->
 		    {keypos, 2},
 		    {repair, mnesia_monitor:get_env(auto_repair)} 
 		    | DetsProps ],
-	    mnesia_monitor:open_dets(Tab, Args)
+	    mnesia_monitor:open_dets(Tab, Args);
+	element(1,Storage) == ext ->
+	    {ext, Alias, Mod} = Storage,
+	    Mod:create_table(Alias, Tab, [])
     end,
     insert_op(Tid, ignore, {op, create_table, TabDef}, InPlace, InitBy);
 
@@ -659,9 +751,10 @@ insert_op(Tid, _, {op, create_table, TabDef}, InPlace, InitBy) ->
     Tab = Cs#cstruct.name,
     Storage = mnesia_lib:cs_to_storage_type(node(), Cs),
     StorageProps = Cs#cstruct.storage_properties,
+    Semantics = storage_semantics(Storage),
     case InitBy of
 	startup ->
-	    case Storage of
+	    case Semantics of
 		unknown ->
 		    ignore;
 		ram_copies ->
@@ -679,20 +772,10 @@ insert_op(Tid, _, {op, create_table, TabDef}, InPlace, InitBy) ->
 						read_write),
 			    mnesia_log:unsafe_close_log(temp)
 		    end;
-		_ ->
+		disc_only_copies ->
 		    DetsProps = proplists:get_value(dets, StorageProps, []),
 
-		    Args = [{file, mnesia_lib:tab2dat(Tab)},
-			    {type, mnesia_lib:disk_type(Tab, Cs#cstruct.type)},
-			    {keypos, 2},
-			    {repair, mnesia_monitor:get_env(auto_repair)} 
-			    | DetsProps ],
-		    case mnesia_monitor:open_dets(Tab, Args) of
-			{ok, _} ->
-			    mnesia_monitor:unsafe_close_dets(Tab);
-			{error, Error} ->
-			    exit({"Failed to create dets table", Error})
-		    end
+		    try_create_disc_only_copy(Storage, Tab, Cs, DetsProps)
 	    end;
 	_ ->
 	    Copies = mnesia_lib:copy_holders(Cs),
@@ -715,7 +798,7 @@ insert_op(Tid, _, {op, create_table, TabDef}, InPlace, InitBy) ->
 			false ->
 			    mnesia_lib:set({Tab, where_to_read}, node())
 		    end,
-		    case Storage of
+		    case Semantics of
 			ram_copies ->
 			    ignore;
 			_ ->
@@ -838,7 +921,7 @@ insert_op(Tid, _, {op, del_table_copy, Storage, Node, TabDef}, InPlace, InitBy)
 	    insert_cstruct(Tid, Cs, true, InPlace, InitBy);
         Tab /= schema ->
 	    mnesia_controller:del_active_replica(Tab, Node),
-	    mnesia_lib:del({Tab, Storage}, Node),
+	    mnesia_lib:del({Tab, storage_alias(Storage)}, Node),
 	    if
 		Node == node() ->
 		    case Cs#cstruct.local_content of
@@ -896,9 +979,10 @@ insert_op(Tid, _, {op, add_index, Pos, TabDef}, InPlace, InitBy) ->
     Cs = mnesia_schema:list2cs(TabDef),
     Tab = insert_cstruct(Tid, Cs, true, InPlace, InitBy),
     Storage = mnesia_lib:cs_to_storage_type(node(), Cs),
+    Semantics = storage_semantics(Storage),
     case InitBy of
-	startup when Storage == disc_only_copies ->
-	    true = open_files(Tab, Storage, InPlace, InitBy),
+	startup when Semantics == disc_only_copies ->
+	    true = open_files(Tab, Semantics, Storage, InPlace, InitBy),
 	    mnesia_index:init_indecies(Tab, Storage, [Pos]);
 	startup ->
 	    ignore;
@@ -919,6 +1003,8 @@ insert_op(Tid, _, {op, del_index, Pos, TabDef}, InPlace, InitBy) ->
 	    mnesia_index:del_index_table(Tab, Storage, Pos);
 	startup ->
 	    ignore;
+        _ when element(1, Storage) == ext ->
+	    mnesia_index:del_index_table(Tab, Storage, Pos);
 	_ ->
 	    mnesia_index:del_index_table(Tab, Storage, Pos)
     end,
@@ -958,19 +1044,68 @@ insert_op(Tid, _, {op, change_table_frag, _Change, TabDef}, InPlace, InitBy) ->
     Cs = mnesia_schema:list2cs(TabDef),
     insert_cstruct(Tid, Cs, true, InPlace, InitBy).
 
-open_files(Tab, Storage, UpdateInPlace, InitBy)
-  when Storage /= unknown, Storage /= ram_copies ->
+
+storage_semantics({ext, Alias, Mod}) ->
+    Mod:semantics(Alias, storage);
+storage_semantics(Storage) when is_atom(Storage) ->
+    Storage.
+
+storage_alias({ext, Alias, _}) ->
+    Alias;
+storage_alias(Storage) when is_atom(Storage) ->
+    Storage.
+
+change_disc_to_ram(Tab, Cs, FromS, ToS, Logtmp, InitBy) ->
+    disc_delete_indecies(Tab, Cs, FromS),
+    case InitBy of
+	startup ->
+	    ignore;
+	_ ->
+	    %% ram table will already have been created
+	    Tab = ets:info(Tab, name),  %% assertion
+	    load_from_logfile(ToS, Tab, Logtmp),
+	    PosList = Cs#cstruct.index,
+	    mnesia_index:init_indecies(Tab, ToS, PosList)
+    end,
+    disc_delete_table(Tab, FromS).
+
+
+try_create_disc_only_copy({ext,Alias,Mod}, Tab, Cs, _) ->
+    Mod:create_table(Alias, Tab, mnesia_schema:cs2list(Cs));
+try_create_disc_only_copy(disc_only_copies, Tab, Cs, DetsProps) ->
+    Args = [{file, mnesia_lib:tab2dat(Tab)},
+	    {type, mnesia_lib:disk_type(Tab, Cs#cstruct.type)},
+	    {keypos, 2},
+	    {repair, mnesia_monitor:get_env(auto_repair)}
+	    | DetsProps],
+    case mnesia_monitor:open_dets(Tab, Args) of
+	{ok, _} ->
+	    mnesia_monitor:unsafe_close_dets(Tab);
+	{error, Error} ->
+	    exit({"Failed to create dets table", Error})
+    end.
+
+restore_indexes(Tab, ToS, Cs) ->
+    PosList = Cs#cstruct.index,
+    mnesia_index:init_indecies(Tab, ToS, PosList).
+
+
+open_files(Tab, Storage, UpdateInPlace, InitBy) ->
+    open_files(Tab, storage_semantics(Storage), Storage, UpdateInPlace, InitBy).
+
+open_files(Tab, Semantics, Storage, UpdateInPlace, InitBy)
+  when Storage /= unknown, Semantics /= ram_copies ->
     case get({?MODULE, Tab}) of
 	undefined ->
 	    case ?catch_val({Tab, setorbag}) of
 		{'EXIT', _} ->
 		    false;
 		Type ->
-		    case Storage of
-			disc_copies when Tab /= schema ->
+		    Cs = val({Tab, cstruct}),
+		    if Semantics  == disc_copies, Tab /= schema ->
 			    Bool = open_disc_copies(Tab, InitBy),
 			    Bool;
-			_ ->
+		       Storage == disc_only_copies; Tab == schema ->
 			    Props = val({Tab, storage_properties}),
 			    DetsProps = proplists:get_value(dets, Props, []),
 			    Fname = prepare_open(Tab, UpdateInPlace),
@@ -981,6 +1116,12 @@ open_files(Tab, Storage, UpdateInPlace, InitBy)
 				    | DetsProps],
 			    {ok, _} = mnesia_monitor:open_dets(Tab, Args),
 			    put({?MODULE, Tab}, {opened_dumper, dat}),
+			    true;
+		       element(1, Storage) == ext ->
+			    {ext, Alias, Mod} = Storage,
+			    Mod:load_table(Alias, Tab, InitBy,
+					   mnesia_schema:cs2list(Cs)),
+			    put({?MODULE, Tab}, {opened_dumper, ext}),
 			    true
 		    end
 	    end;
@@ -989,7 +1130,7 @@ open_files(Tab, Storage, UpdateInPlace, InitBy)
 	{opened_dumper, _} ->
 	    true
     end;
-open_files(_Tab, _Storage, _UpdateInPlace, _InitBy) ->
+open_files(_Tab, _Semantics, _Storage, _UpdateInPlace, _InitBy) ->
     false.
 
 open_disc_copies(Tab, InitBy) ->
@@ -1076,12 +1217,13 @@ close_files(InPlace, Outcome, InitBy, [{{?MODULE, Tab}, already_dumped} | Tail])
     close_files(InPlace, Outcome, InitBy, Tail);
 close_files(InPlace, Outcome, InitBy, [{{?MODULE, Tab}, {opened_dumper, Type}} | Tail]) ->
     erase({?MODULE, Tab}),
-    case val({Tab, storage_type}) of
+    Storage = val({Tab, storage_type}),
+    case storage_semantics(Storage) of
 	disc_only_copies when InitBy /= startup ->
 	    ignore;
-	disc_copies when Tab /= schema ->
+	disc_copies when Storage /= unknown, Tab /= schema ->
 	    mnesia_log:close_log({?MODULE,Tab});
-	Storage ->
+	_ ->
 	    do_close(InPlace, Outcome, Tab, Type, Storage)
     end,
     close_files(InPlace, Outcome, InitBy, Tail);
@@ -1093,11 +1235,16 @@ close_files(_, _, _InitBy, []) ->
 
 %% If storage is unknown during close clean up files, this can happen if timing
 %% is right and dirty_write conflicts with schema operations.
+do_close(_, _, Tab, ext, {ext,Alias,Mod}) ->
+    Mod:close_table(Alias, Tab);
 do_close(_, _, Tab, dcl, unknown) ->
     mnesia_log:close_log({?MODULE,Tab}),
     file:delete(mnesia_lib:tab2dcl(Tab));
 do_close(_, _, Tab, dcl, _) ->  %% To be safe, can it happen?
     mnesia_log:close_log({?MODULE,Tab});
+do_close(_, _, _Tab, ext, unknown) ->
+    %% Not sure what to do here, but let's not crash
+    ok;
 
 do_close(InPlace, Outcome, Tab, dat, Storage) ->
     mnesia_monitor:close_dets(Tab),
@@ -1148,7 +1295,8 @@ temp_set_master_nodes() ->
     Tabs = val({schema, local_tables}),
     Masters = [{Tab, (val({Tab, disc_copies}) ++
 		      val({Tab, ram_copies}) ++
-		      val({Tab, disc_only_copies})) -- [node()]}
+		      val({Tab, disc_only_copies}) ++
+		      external_copies(Tab)) -- [node()]}
 	       || Tab <- Tabs],
     %% UseDir = false since we don't want to remember these
     %% masternodes and we are running (really soon anyway) since we want this
@@ -1156,6 +1304,13 @@ temp_set_master_nodes() ->
     mnesia_recover:log_master_nodes(Masters, false, yes),
     ok.
 
+external_copies(Tab) ->
+    case ?catch_val({Tab, external_copies}) of
+	{'EXIT',_} -> [];
+	Ext ->
+	    lists:concat([Ns || {_, Ns} <- Ext])
+    end.
+
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 %% Raw dump of table. Dumper must have unique access to the ets table.
 
@@ -1207,6 +1362,57 @@ raw_named_dump_table(Tab, Ftype) ->
 raw_dump_table(DetsRef, EtsRef) ->
     dets:from_ets(DetsRef, EtsRef).
 
+dump_to_logfile(Storage, Tab) ->
+    case mnesia_monitor:use_dir() of
+	true ->
+	    Logtmp = mnesia_lib:tab2logtmp(Tab),
+	    file:delete(Logtmp),
+	    case disk_log:open([{name, make_ref()},
+				{file, Logtmp},
+				{repair, false},
+				{linkto, self()}]) of
+		{ok, Fd} ->
+		    mnesia_lib:db_fixtable(Storage, Tab, true),
+		    try do_dump_to_logfile(Storage, Tab, Fd)
+		    after
+			mnesia_lib:db_fixtable(Storage, Tab, false)
+		    end;
+		{error, _} = Error ->
+		    Error
+	    end;
+	false ->
+	    {error, {has_no_disc, node()}}
+    end.
+
+do_dump_to_logfile(Storage, Tab, Fd) ->
+    Pat = [{'_',[],['$_']}],
+    log_terms(mnesia_lib:db_select_init(Storage, Tab, Pat, 100), Storage, Tab, Pat, Fd).
+
+log_terms({Objs, Cont}, Storage, Tab, Pat, Fd) ->
+    ok = disk_log:alog_terms(Fd, Objs),
+    log_terms(mnesia_lib:db_select_cont(Storage, Cont, '_'), Storage, Tab, Pat, Fd);
+log_terms('$end_of_table', _, _, _, Fd) ->
+    disk_log:close(Fd).
+
+load_from_logfile(Storage, Tab, F) ->
+    case disk_log:open([{name, make_ref()},
+			{file, F},
+			{repair, true},
+			{linkto, self()}]) of
+	{ok, Fd} ->
+	    chunk_from_log(disk_log:chunk(Fd, start), Fd, Storage, Tab);
+	{error, _} = E ->
+	    E
+    end.
+
+chunk_from_log({Cont, Terms}, Fd, Storage, Tab) ->
+    _ = [mnesia_lib:db_put(Storage, Tab, T) || T <- Terms],
+    chunk_from_log(disk_log:chunk(Fd, Cont), Fd, Storage, Tab);
+chunk_from_log(eof, _, _, _) ->
+    ok.
+
+
+
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 %% Load regulator
 %%
diff --git a/lib/mnesia/src/mnesia_schema.erl b/lib/mnesia/src/mnesia_schema.erl
index d482f1be43..19b578f551 100644
--- a/lib/mnesia/src/mnesia_schema.erl
+++ b/lib/mnesia/src/mnesia_schema.erl
@@ -69,6 +69,7 @@
          insert_cstruct/3,
 	 is_remote_member/1,
          list2cs/1,
+         list2cs/2,
          lock_schema/0,
          merge_schema/0,
          merge_schema/1,
@@ -116,7 +117,8 @@
 	 do_delete_table/1,
 	 do_read_table_property/2,
 	 do_delete_table_property/2,
- 	 do_write_table_property/2]).
+         do_write_table_property/2,
+         do_change_table_copy_type/3]).
 
 -include("mnesia.hrl").
 -include_lib("kernel/include/file.hrl").
@@ -144,6 +146,7 @@ init(IgnoreFallback) ->
     verbose("Schema initiated from: ~p~n", [Source]),
     set({schema, tables}, []),
     set({schema, local_tables}, []),
+    do_set_schema(schema),
     Tabs = set_schema(?ets_first(schema)),
     lists:foreach(fun(Tab) -> clear_whereabouts(Tab) end, Tabs),
     set({schema, where_to_read}, node()),
@@ -203,6 +206,7 @@ do_set_schema(Tab, Cs) ->
     set({Tab, ram_copies}, Cs#cstruct.ram_copies),
     set({Tab, disc_copies}, Cs#cstruct.disc_copies),
     set({Tab, disc_only_copies}, Cs#cstruct.disc_only_copies),
+    set({Tab, external_copies}, Cs#cstruct.external_copies),
     set({Tab, load_order}, Cs#cstruct.load_order),
     set({Tab, access_mode}, Cs#cstruct.access_mode),
     set({Tab, majority}, Cs#cstruct.majority),
@@ -218,7 +222,6 @@ do_set_schema(Tab, Cs) ->
     set({Tab, arity}, Arity),
     RecName =  Cs#cstruct.record_name,
     set({Tab, record_name}, RecName),
-    set({Tab, record_validation}, {RecName, Arity, Type}),
     set({Tab, wild_pattern}, wild(RecName, Arity)),
     set({Tab, index}, Cs#cstruct.index),
     %% create actual index tabs later
@@ -227,6 +230,7 @@ do_set_schema(Tab, Cs) ->
     set({Tab, cstruct}, Cs),
     Storage = mnesia_lib:schema_cs_to_storage_type(node(), Cs),
     set({Tab, storage_type}, Storage),
+    set_record_validation(Tab, Storage, RecName, Arity, Type),
     mnesia_lib:add({schema, tables}, Tab),
     Ns = mnesia_lib:cs_to_nodes(Cs),
     case lists:member(node(), Ns) of
@@ -236,7 +240,24 @@ do_set_schema(Tab, Cs) ->
             mnesia_lib:add({schema, local_tables}, Tab);
         false ->
             ignore
-    end.
+    end,
+    set_ext_types(Tab, get_ext_types(), Cs#cstruct.external_copies).
+
+set_record_validation(Tab, {ext,Alias,Mod}, RecName, Arity, Type) ->
+    set({Tab, record_validation}, {RecName, Arity, Type, Alias, Mod});
+set_record_validation(Tab, _, RecName, Arity, Type) ->
+    set({Tab, record_validation}, {RecName, Arity, Type}).
+
+set_ext_types(Tab, ExtTypes, ExtCopies) ->
+    lists:foreach(
+      fun({Type, _} = Key) ->
+	      Nodes = case lists:keyfind(Key, 1, ExtCopies) of
+			  {_, Ns} -> Ns;
+			  false   -> []
+		      end,
+	      set({Tab, Type}, Nodes)
+      end, ExtTypes).
+
 
 wild(RecName, Arity) ->
     Wp0 = list_to_tuple(lists:duplicate(Arity, '_')),
@@ -603,8 +624,9 @@ read_cstructs_from_disc() ->
 		    {type, set}],
 	    case dets:open_file(make_ref(), Args) of
 		{ok, Tab} ->
+                    ExtTypes = get_ext_types_disc(),
 		    Fun = fun({_, _, List}) ->
-				  {continue, list2cs(List)}
+				  {continue, list2cs(List, ExtTypes)}
 			  end,
 		    Cstructs = dets:traverse(Tab, Fun),
 		    dets:close(Tab),
@@ -684,7 +706,7 @@ do_insert_schema_ops(_Store, []) ->
 
 api_list2cs(List) when is_list(List) ->
     Name = pick(unknown, name, List, must),
-    Keys = check_keys(Name, List, record_info(fields, cstruct)),
+    Keys = check_keys(Name, List),
     check_duplicates(Name, Keys),
     list2cs(List);
 api_list2cs(Other) ->
@@ -729,6 +751,14 @@ cs2list({8,Minor}, Cs) when Minor =:= 2; Minor =:= 1 ->
 	    cookie,version],
     rec2list(Tags, Orig, 2, Cs).
 
+rec2list([external_copies | Tags], Orig0, Pos, Rec) ->
+    Orig = case Orig0 of
+	       [external_copies|Rest] -> Rest;
+	       _ -> Orig0
+	   end,
+    Val = element(Pos, Rec),
+    [{Alias, Ns} || {{Alias,_}, Ns} <- Val]
+	++ rec2list(Tags, Orig, Pos+1, Rec);
 rec2list([Tag | Tags], [Tag | Orig], Pos, Rec) ->
     Val = element(Pos, Rec),
     [{Tag, Val} | rec2list(Tags, Orig, Pos + 1, Rec)];
@@ -751,14 +781,19 @@ convert_cs(Version, Cs) ->
     Fields = [Value || {_, Value} <- cs2list(Version, Cs)],
     list_to_tuple([cstruct|Fields]).
 
-list2cs(List) when is_list(List) ->
+list2cs(List) ->
+    list2cs(List, get_ext_types()).
+
+list2cs(List, ExtTypes) when is_list(List) ->
     Name = pick(unknown, name, List, must),
     Type = pick(Name, type, List, set),
     Rc0 = pick(Name, ram_copies, List, []),
     Dc = pick(Name, disc_copies, List, []),
     Doc = pick(Name, disc_only_copies, List, []),
-    Rc = case {Rc0, Dc, Doc} of
-             {[], [], []} -> [node()];
+
+    Ext = pick_external_copies(List, ExtTypes),
+    Rc = case {Rc0, Dc, Doc, Ext} of
+             {[], [], [], []} -> [node()];
              _ -> Rc0
          end,
     LC = pick(Name, local_content, List, false),
@@ -804,24 +839,47 @@ list2cs(List) when is_list(List) ->
     DetsOpts = proplists:get_value(dets, BEProps, []),
     is_list(DetsOpts) orelse mnesia:abort({badarg, Name, {dets, DetsOpts}}),
     [CheckProp(Prop, BadDetsOpts) || Prop <- DetsOpts],
-    #cstruct{name = Name,
-             ram_copies = Rc,
-             disc_copies = Dc,
-             disc_only_copies = Doc,
-             type = Type,
-             index = Ix2,
-             snmp = Snmp,
-             load_order = LoadOrder,
-             access_mode = AccessMode,
-	     majority = Majority,
-             local_content = LC,
-	     record_name = RecName,
-             attributes = Attrs,
-             user_properties = lists:sort(UserProps),
-	     frag_properties = lists:sort(Frag),
-	     storage_properties = lists:sort(BEProps),
-             cookie = Cookie,
-             version = Version}.
+
+    case lists:keymember(mnesia, 1, application:which_applications()) of
+        true ->
+            Keys = check_keys(Name, List),
+            check_duplicates(Name, Keys);
+        false ->
+            %% check_keys/2 cannot be executed when mnesia is not
+            %% running, due to it not being possible to read what ext
+            %% backends are loaded.
+            %%% this doesn't work - disabled for now:
+	    %%%Keys = check_keys(Name, List, record_info(fields, cstruct)),
+	    %%%check_duplicates(Name, Keys)
+            ignore
+    end,
+
+    Cs0 = #cstruct{name = Name,
+		   ram_copies = Rc,
+		   disc_copies = Dc,
+		   disc_only_copies = Doc,
+		   external_copies = Ext,
+		   type = Type,
+		   index = Ix,
+		   snmp = Snmp,
+		   load_order = LoadOrder,
+		   access_mode = AccessMode,
+		   majority = Majority,
+		   local_content = LC,
+		   record_name = RecName,
+		   attributes = Attrs,
+		   user_properties = lists:sort(UserProps),
+		   frag_properties = lists:sort(Frag),
+                   storage_properties = lists:sort(BEProps),
+		   cookie = Cookie,
+		   version = Version},
+    case Ix of
+	[] -> Cs0;
+	[_|_] ->
+	    Cs0#cstruct{index = Ix2}
+    end;
+list2cs(Other, _ExtTypes) ->
+    mnesia:abort({badarg, Other}).
 
 pick(Tab, Key, List, Default) ->
     case lists:keysearch(Key, 1, List) of
@@ -835,6 +893,31 @@ pick(Tab, Key, List, Default) ->
 	    mnesia:abort({bad_type, Tab, BadArg})
     end.
 
+pick_external_copies(_List, []) ->
+    [];
+pick_external_copies(List, ExtTypes) ->
+    lists:foldr(
+      fun({K, Val}, Acc) ->
+	      case lists:keyfind(K, 1, ExtTypes) of
+		  false ->
+		      Acc;
+		  {_, Mod} ->
+		      [{{K,Mod}, Val}|Acc]
+	      end
+      end, [], List).
+
+expand_storage_type(S) when S==ram_copies;
+			    S==disc_copies;
+			    S==disc_only_copies ->
+    S;
+expand_storage_type(S) ->
+    case lists:keyfind(S, 1, get_ext_types()) of
+	false ->
+	    mnesia:abort({bad_type, {storage_type, S}});
+	{Alias, Mod} ->
+	    {ext, Alias, Mod}
+    end.
+
 get_ext_types() ->
     get_schema_user_property(mnesia_backend_types).
 
@@ -854,6 +937,32 @@ get_schema_user_property(Key) ->
 	    Types
     end.
 
+get_ext_types_disc() ->
+    try get_ext_types_disc_()
+    catch
+	error:_ ->[]
+    end.
+
+get_ext_types_disc_() ->
+    case mnesia_schema:remote_read_schema() of
+        {ok, _, Prop} ->
+            K1 = user_properties,
+            case lists:keyfind(K1, 1, Prop) of
+                {K1, UserProp} ->
+                    K2 = mnesia_backend_types,
+                    case lists:keyfind(K2, 1, UserProp) of
+                        {K2, Types} ->
+                            Types;
+                        _ ->
+                            []
+                    end;
+                _ ->
+                    []
+            end;
+        _ ->
+            []
+    end.
+
 %% Convert attribute name to integer if neccessary
 attr_tab_to_pos(_Tab, Pos) when is_integer(Pos) ->
     Pos;
@@ -875,8 +984,18 @@ attr_to_pos(Attr, [_ | Attrs], Pos) ->
 attr_to_pos(Attr, _, _) ->
     mnesia:abort({bad_type, Attr}).
 
+check_keys(Tab, Attrs) ->
+    Types = [T || {T,_} <- get_ext_types()],
+    check_keys(Tab, Attrs, Types ++ record_info(fields, cstruct)).
+
 check_keys(Tab, [{Key, _Val} | Tail], Items) ->
-    case lists:member(Key, Items) of
+    Key1 = if
+               is_tuple(Key) ->
+                   element(1, Key);
+               true ->
+                   Key
+           end,
+    case lists:member(Key1, Items) of
         true ->  [Key | check_keys(Tab, Tail, Items)];
         false -> mnesia:abort({badarg, Tab, Key})
     end;
@@ -902,7 +1021,55 @@ has_duplicates([]) ->
 %% This is the only place where we check the validity of data
 verify_cstruct(#cstruct{} = Cs) ->
     assert_correct_cstruct(Cs),
-    Cs.
+    Cs1 = verify_external_copies(Cs),
+    assert_correct_cstruct(Cs1),
+    Cs1.
+
+verify_external_copies(#cstruct{external_copies = []} = Cs) ->
+    Cs;
+verify_external_copies(#cstruct{name = Tab, external_copies = EC} = Cs) ->
+    Bad = {bad_type, Tab, {external_copies, EC}},
+    AllECNodes = lists:concat([Ns || {_, Ns} <- EC,
+                                     is_list(Ns)]),
+    verify(true, length(lists:usort(AllECNodes)) == length(AllECNodes), Bad),
+    CsL = cs2list(Cs),
+    CsL1 = lists:foldl(
+	     fun({{Alias, Mod}, Ns} = _X, CsLx) ->
+		     BadTab = fun(Why) ->
+				      {Why, Tab, {{ext, Alias, Mod},Ns}}
+			      end,
+		     verify(atom, mnesia_lib:etype(Mod), BadTab),
+		     verify(true, fun() ->
+					  lists:all(fun is_atom/1, Ns)
+				  end, BadTab),
+		     check_semantics(Mod, Alias, BadTab, Cs),
+		     try Mod:check_definition(Alias, Tab, Ns, CsLx) of
+			 ok ->
+			     CsLx;
+			 {ok, CsLx1} ->
+			     CsLx1;
+			 {error, Reason} ->
+			     mnesia:abort(BadTab(Reason))
+		     catch
+			 error:E ->
+			     mnesia:abort(BadTab(E))
+		     end;
+		(_, CsLx) ->
+		     CsLx
+	     end, CsL, EC),
+    list2cs(CsL1).
+
+check_semantics(Mod, Alias, BadTab, #cstruct{type = Type}) ->
+    Ext = {ext, Alias, Mod},
+    case lists:member(mnesia_lib:semantics(Ext, storage), [ram_copies, disc_copies,
+							   disc_only_copies]) of
+	false -> mnesia:abort(BadTab(invalid_storage));
+	true  -> ok
+    end,
+    case lists:member(Type, mnesia_lib:semantics(Ext, types)) of
+	false -> mnesia:abort(BadTab(bad_type));
+	true  -> ok
+    end.
 
 assert_correct_cstruct(Cs) when is_record(Cs, cstruct) ->
     verify_nodes(Cs),
@@ -1011,12 +1178,22 @@ verify_nodes(Cs) ->
     Ram = Cs#cstruct.ram_copies,
     Disc = Cs#cstruct.disc_copies,
     DiscOnly = Cs#cstruct.disc_only_copies,
+    Ext = lists:append([Ns || {_,Ns} <- Cs#cstruct.external_copies]),
     LoadOrder = Cs#cstruct.load_order,
 
     verify({alt, [nil, list]}, mnesia_lib:etype(Ram),
 	   {bad_type, Tab, {ram_copies, Ram}}),
     verify({alt, [nil, list]}, mnesia_lib:etype(Disc),
 	   {bad_type, Tab, {disc_copies, Disc}}),
+    lists:foreach(
+      fun({BE, Ns}) ->
+	      verify({alt, [nil, list]}, mnesia_lib:etype(Ns),
+		     {bad_type, Tab, {BE, Ns}}),
+	      lists:foreach(fun(N) ->
+				    verify(atom, mnesia_lib:etype(N),
+					   {bad_type, Tab, {BE, Ns}})
+			    end, Ns)
+      end, Cs#cstruct.external_copies),
     case Tab of
 	schema ->
 	    verify([], DiscOnly, {bad_type, Tab, {disc_only_copies, DiscOnly}});
@@ -1028,12 +1205,15 @@ verify_nodes(Cs) ->
     verify(integer, mnesia_lib:etype(LoadOrder),
 	   {bad_type, Tab, {load_order, LoadOrder}}),
 
-    Nodes = Ram ++ Disc ++ DiscOnly,
+    Nodes = Ram ++ Disc ++ DiscOnly ++ Ext,
     verify(list, mnesia_lib:etype(Nodes),
 	   {combine_error, Tab,
-	    [{ram_copies, []}, {disc_copies, []}, {disc_only_copies, []}]}),
+	    [{ram_copies, []}, {disc_copies, []},
+	     {disc_only_copies, []}, {external_copies, []}]}),
     verify(false, has_duplicates(Nodes), {combine_error, Tab, Nodes}),
-    AtomCheck = fun(N) -> verify(atom, mnesia_lib:etype(N), {bad_type, Tab, N}) end,
+    AtomCheck = fun(N) ->
+			verify(atom, mnesia_lib:etype(N), {bad_type, Tab, N})
+		end,
     lists:foreach(AtomCheck, Nodes).
 
 verify(Expected, Fun, Error) when is_function(Fun) ->
@@ -1216,25 +1396,29 @@ backend_types() ->
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 %% Here's the real interface function to create a table
 
-create_table(TabDef) ->
-    schema_transaction(fun() -> do_multi_create_table(TabDef) end).
+create_table([_|_] = TabDef) ->
+    schema_transaction(fun() -> do_multi_create_table(TabDef) end);
+create_table(Arg) -> {aborted, {badarg, Arg}}.
 
 %% And the corresponding do routines ....
 
 do_multi_create_table(TabDef) ->
     get_tid_ts_and_lock(schema, write),
     ensure_writable(schema),
+    do_create_table(TabDef),
+    ok.
+
+do_create_table(TabDef) when is_list(TabDef) ->
     Cs = api_list2cs(TabDef),
     case Cs#cstruct.frag_properties of
 	[] ->
-	    do_create_table(Cs);
+	    do_create_table_1(Cs);
 	_Props ->
 	    CsList = mnesia_frag:expand_cstruct(Cs),
-	    lists:foreach(fun do_create_table/1, CsList)
-    end,
-    ok.
+	    lists:foreach(fun do_create_table_1/1, CsList)
+    end.
 
-do_create_table(Cs) ->
+do_create_table_1(Cs) ->
     {_Mod, _Tid, Ts} =  get_tid_ts_and_lock(schema, none),
     Store = Ts#tidstore.store,
     do_insert_schema_ops(Store, make_create_table(Cs)).
@@ -1495,8 +1679,34 @@ new_cs(Cs, Node, disc_copies, del) ->
 new_cs(Cs, Node, disc_only_copies, del) ->
     Cs#cstruct{disc_only_copies =
                lists:delete(Node , Cs#cstruct.disc_only_copies)};
-new_cs(Cs, _Node, Storage, _Op) ->
-    mnesia:abort({badarg, Cs#cstruct.name, Storage}).
+new_cs(#cstruct{external_copies = ExtCps} = Cs, Node, Storage0, Op) ->
+    Storage = case Storage0 of
+		  {ext, Alias, _} -> Alias;
+		  Alias -> Alias
+	      end,
+    ExtTypes = get_ext_types(),
+    case lists:keyfind(Storage, 1, ExtTypes) of
+	false ->
+	    mnesia:abort({badarg, Cs#cstruct.name, Storage});
+	{_, Mod} ->
+	    Key = {Storage, Mod},
+	    case {lists:keymember(Key, 1, ExtCps), Op} of
+		{false, del} ->
+		    Cs;
+		{false, add} ->
+		    Cs#cstruct{external_copies = [{Key, [Node]}|ExtCps]};
+		{true, _} ->
+		    F = fun({K, Ns}) when K == Key ->
+				case Op of
+				    del -> {K, lists:delete(Node, Ns)};
+				    add -> {K, opt_add(Node, Ns)}
+				end;
+			   (X) ->
+				X
+			end,
+		    Cs#cstruct{external_copies = lists:map(F, ExtCps)}
+	    end
+    end.
 
 
 opt_add(N, L) -> [N | lists:delete(N, L)].
@@ -1559,9 +1769,11 @@ make_change_table_copy_type(Tab, Node, ToS) ->
     Cs = incr_version(val({Tab, cstruct})),
     FromS = mnesia_lib:storage_type_at_node(Node, Tab),
 
-    case compare_storage_type(false, FromS, ToS) of
+    ToSExp = expand_storage_type(ToS),
+
+    case compare_storage_type(false, FromS, ToSExp) of
 	{same, _} ->
-	    mnesia:abort({already_exists, Tab, Node, ToS});
+	    mnesia:abort({already_exists, Tab, Node, ToSExp});
 	{diff, _} ->
 	    ignore;
 	incompatible ->
@@ -1570,7 +1782,7 @@ make_change_table_copy_type(Tab, Node, ToS) ->
 
     Cs2 = new_cs(Cs, Node, FromS, del),
     Cs3 = verify_cstruct(new_cs(Cs2, Node, ToS, add)),
-    [{op, change_table_copy_type, Node, FromS, ToS, vsn_cs2list(Cs3)}].
+    [{op, change_table_copy_type, Node, FromS, ToSExp, vsn_cs2list(Cs3)}].
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 %% change index functions ....
@@ -1614,9 +1826,8 @@ make_del_table_index(Tab, Pos) ->
     Cs = incr_version(val({Tab, cstruct})),
     ensure_active(Cs),
     Ix = Cs#cstruct.index,
-    verify(true, lists:member(Pos, Ix), {no_exists, Tab, Pos}),
-    Cs2 = Cs#cstruct{index = lists:delete(Pos, Ix)},
-    verify_cstruct(Cs2),
+    verify(true, lists:keymember(Pos, 1, Ix), {no_exists, Tab, Pos}),
+    Cs2 = verify_cstruct(Cs#cstruct{index = lists:keydelete(Pos, 1, Ix)}),
     [{op, del_index, Pos, vsn_cs2list(Cs2)}].
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@@ -1684,20 +1895,21 @@ make_transform(Tab, Fun, NewAttrs, NewRecName) ->
     Cs = incr_version(val({Tab, cstruct})),
     ensure_active(Cs),
     ensure_writable(Tab),
-    case mnesia_lib:val({Tab, index}) of
+    case Cs#cstruct.index of
 	[] ->
 	    Cs2 = verify_cstruct(
                     Cs#cstruct{attributes = NewAttrs,
                                record_name = NewRecName}),
 	    [{op, transform, Fun, vsn_cs2list(Cs2)}];
 	PosList ->
-	    DelIdx = fun(Pos, Ncs) ->
+	    DelIdx = fun({Pos,_,_}, Ncs) ->
 			     Ix = Ncs#cstruct.index,
-			     Ncs1 = Ncs#cstruct{index = lists:delete(Pos, Ix)},
+			     Ix2 = lists:keydelete(Pos, 1, Ix),
+			     Ncs1 = Ncs#cstruct{index = Ix2},
 			     Op = {op, del_index, Pos, vsn_cs2list(Ncs1)},
 			     {Op, Ncs1}
 		     end,
-	    AddIdx = fun(Pos, Ncs) ->
+	    AddIdx = fun({_,_,_} = Pos, Ncs) ->
 			     Ix = Ncs#cstruct.index,
 			     Ix2 = lists:sort([Pos | Ix]),
 			     Ncs1 = Ncs#cstruct{index = Ix2},
@@ -1797,6 +2009,7 @@ write_table_property(Tab, Prop) when is_tuple(Prop), size(Prop) >= 1 ->
     schema_transaction(fun() -> do_write_table_property(Tab, Prop) end);
 write_table_property(Tab, Prop) ->
     {aborted, {bad_type, Tab, Prop}}.
+
 do_write_table_property(Tab, Prop) ->
     TidTs = get_tid_ts_and_lock(schema, write),
     {_, _, Ts} = TidTs,
@@ -2105,6 +2318,11 @@ prepare_op(Tid, {op, create_table, TabDef}, _WaitFor) ->
 	    create_disc_only_table(Tab,Cs),
 	    insert_cstruct(Tid, Cs, false),
 	    {true, optional};
+	{ext, Alias, Mod} ->
+	    mnesia_lib:set({Tab, create_table},true),
+            create_external_table(Alias, Tab, Mod, Cs),
+	    insert_cstruct(Tid, Cs, false),
+	    {true, optional};
         unknown -> %% No replica on this node
 	    mnesia_lib:set({Tab, create_table},true),
 	    insert_cstruct(Tid, Cs, false),
@@ -2173,6 +2391,12 @@ prepare_op(_Tid, {op, change_table_copy_type,  N, FromS, ToS, TabDef}, _WaitFor)
 
     NotActive = mnesia_lib:not_active_here(Tab),
 
+    if Tab =/= schema ->
+	    check_if_disc_required(FromS, ToS);
+       true ->
+	    ok
+    end,
+
     if
 	NotActive == true ->
 	    mnesia:abort({not_active, Tab, node()});
@@ -2212,6 +2436,15 @@ prepare_op(_Tid, {op, change_table_copy_type,  N, FromS, ToS, TabDef}, _WaitFor)
 		    mnesia:abort({combine_error, Tab, ToS})
 	    end;
 
+	element(1,FromS) == ext; element(1,ToS) == ext ->
+	    if ToS == ram_copies ->
+		    create_ram_table(Tab, Cs);
+	       true ->
+		    ok
+	    end,
+            mnesia_dumper:dump_to_logfile(FromS, Tab),
+            mnesia_checkpoint:tm_change_table_copy_type(Tab, FromS, ToS);
+
 	FromS == ram_copies ->
 	    case mnesia_monitor:use_dir() of
 		true ->
@@ -2237,6 +2470,7 @@ prepare_op(_Tid, {op, change_table_copy_type,  N, FromS, ToS, TabDef}, _WaitFor)
 
 	FromS == disc_copies, ToS == disc_only_copies ->
 	    mnesia_dumper:raw_named_dump_table(Tab, dmp);
+
 	FromS == disc_only_copies ->
 	    Type = Cs#cstruct.type,
 	    create_ram_table(Tab, Cs),
@@ -2248,6 +2482,7 @@ prepare_op(_Tid, {op, change_table_copy_type,  N, FromS, ToS, TabDef}, _WaitFor)
 		    Err = "Failed to copy disc data to ram",
 		    mnesia:abort({system_limit, Tab, {Err,Reason}})
 	    end;
+
 	true ->
 	    ignore
     end,
@@ -2311,6 +2546,8 @@ prepare_op(_Tid, {op, transform, Fun, TabDef}, _WaitFor) ->
                     {true, Objs, mandatory}
 	    catch _:Reason ->
 		    mnesia_lib:db_fixtable(Storage, Tab, false),
+		    mnesia_lib:important("Transform function failed: '~p' in '~p'",
+					 [Reason, erlang:get_stacktrace()]),
                     exit({"Bad transform function", Tab, Fun, node(), Reason})
             end
     end;
@@ -2327,6 +2564,22 @@ prepare_op(_Tid, {op, merge_schema, TabDef}, _WaitFor) ->
 prepare_op(_Tid, _Op, _WaitFor) ->
     {true, optional}.
 
+check_if_disc_required(FromS, ToS) ->
+    FromSem = mnesia_lib:semantics(FromS, storage),
+    ToSem = mnesia_lib:semantics(ToS, storage),
+    case {FromSem, ToSem} of
+	{ram_copies, _} when ToSem == disc_copies;
+			     ToSem == disc_only_copies ->
+	    case mnesia_monitor:use_dir() of
+		true ->
+		    ok;
+		false ->
+		    mnesia:abort({has_no_disc, node()})
+	    end;
+	_ ->
+	    ok
+    end.
+
 create_ram_table(Tab, #cstruct{type=Type, storage_properties=Props}) ->
     EtsOpts = proplists:get_value(ets, Props, []),
     Args = [{keypos, 2}, public, named_table, Type | EtsOpts],
@@ -2368,6 +2621,14 @@ create_disc_only_table(Tab, #cstruct{type=Type, storage_properties=Props}) ->
 	    mnesia:abort({system_limit, Tab, {Err,Reason}})
     end.
 
+create_external_table(Alias, Tab, Mod, Cs) ->
+    case mnesia_monitor:unsafe_create_external(Tab, Alias, Mod, Cs) of
+	ok ->
+	    ok;
+	{error,Reason} ->
+	    Err = "Failed to create external table",
+	    mnesia:abort({system_limit, Tab, {Err,Reason}})
+    end.
 
 receive_sync([], Pids) ->
     Pids;
@@ -2502,7 +2763,10 @@ undo_prepare_op(Tid, {op, create_table, TabDef}) ->
 	    mnesia_monitor:unsafe_close_dets(Tab),
 	    Dat = mnesia_lib:tab2dat(Tab),
 	    %%	    disc_delete_table(Tab, Storage),
-	    file:delete(Dat)
+	    file:delete(Dat);
+        {ext, Alias, Mod} ->
+	    Mod:close_table(Alias, Tab),
+            Mod:delete_table(Alias, Tab)
     end;
 
 undo_prepare_op(Tid, {op, add_table_copy, Storage, Node, TabDef}) ->
@@ -2602,6 +2866,8 @@ ram_delete_table(Tab, Storage) ->
     case Storage of
 	unknown ->
 	    ignore;
+        {ext, _, _} ->
+            ignore;
 	disc_only_copies ->
 	    ignore;
 	_Else ->
@@ -2663,13 +2929,27 @@ purge_known_files([File | Tail], KeepFiles, Dir, Suffixes) ->
 		    ignore;
 		true ->
 		    AbsFile = filename:join([Dir, File]),
-		    file:delete(AbsFile)
-	    end
+                    delete_recursive(AbsFile)
+            end
     end,
     purge_known_files(Tail, KeepFiles, Dir, Suffixes);
 purge_known_files([], _KeepFiles, _Dir, _Suffixes) ->
     ok.
 
+%% Removes a directory or file recursively
+delete_recursive(Path) ->
+    case filelib:is_dir(Path) of
+        true ->
+            {ok, Names} = file:list_dir(Path),
+            lists:foreach(fun(Name) ->
+                                  delete_recursive(filename:join(Path, Name))
+                          end,
+                          Names),
+            file:del_dir(Path);
+        false ->
+            file:delete(Path)
+    end.
+
 has_known_suffix(_File, _Suffixes, true) ->
     true;
 has_known_suffix(File, [Suffix | Tail], false) ->
@@ -2677,11 +2957,33 @@ has_known_suffix(File, [Suffix | Tail], false) ->
 has_known_suffix(_File, [], Bool) ->
     Bool.
 
-known_suffixes() -> real_suffixes() ++ tmp_suffixes().
+known_suffixes() -> known_suffixes(get_ext_types_disc()).
+
+known_suffixes(Ext) -> real_suffixes(Ext) ++ tmp_suffixes(Ext).
 
-real_suffixes() ->  [".DAT", ".LOG", ".BUP", ".DCL", ".DCD"].
+real_suffixes(Ext) ->  [".DAT", ".LOG", ".BUP", ".DCL", ".DCD"] ++ ext_real_suffixes(Ext).
 
-tmp_suffixes() -> [".TMP", ".BUPTMP", ".RET", ".DMP"].
+tmp_suffixes() -> tmp_suffixes(get_ext_types_disc()).
+
+tmp_suffixes(Ext) -> [".TMP", ".BUPTMP", ".RET", ".DMP", "."] ++ ext_tmp_suffixes(Ext).
+
+ext_real_suffixes(Ext) ->
+    try lists:foldl(fun(Mod, Acc) -> Acc++Mod:real_suffixes() end, [],
+		    [M || {_,M} <- Ext])
+    catch
+        error:E ->
+            verbose("Cant find real ext suffixes (~p)~n", [E]),
+            []
+    end.
+
+ext_tmp_suffixes(Ext) ->
+    try lists:foldl(fun(Mod, Acc) -> Acc++Mod:tmp_suffixes() end, [],
+		    [M || {_,M} <- Ext])
+    catch
+        error:E ->
+            verbose("Cant find tmp ext suffixes (~p)~n", [E]),
+            []
+    end.
 
 info() ->
     Tabs = lists:sort(val({schema, tables})),
@@ -2799,12 +3101,12 @@ do_restore(R, BupSchema) ->
 
 arrange_restore(R, Fun, Recs) ->
     R2 = R#r{insert_op = Fun, recs = Recs},
-    case mnesia_bup:iterate(R#r.module, fun restore_items/4, R#r.opaque, R2) of
+    case mnesia_bup:iterate(R#r.module, fun restore_items/5, R#r.opaque, R2) of
 	{ok, R3} -> R3#r.recs;
 	{error, Reason} -> mnesia:abort(Reason)
     end.
 
-restore_items([Rec | Recs], Header, Schema, R) ->
+restore_items([Rec | Recs], Header, Schema, Ext, R) ->
     Tab = element(1, Rec),
     case lists:keysearch(Tab, 1, R#r.tables) of
 	{value, {Tab, Where0, Snmp, RecName}} ->
@@ -2817,13 +3119,13 @@ restore_items([Rec | Recs], Header, Schema, R) ->
 	    {Rest, NRecs} = restore_tab_items([Rec | Recs], Tab,
 					      RecName, Where, Snmp,
 					      R#r.recs, R#r.insert_op),
-	    restore_items(Rest, Header, Schema, R#r{recs = NRecs});
+	    restore_items(Rest, Header, Schema, Ext, R#r{recs = NRecs});
 	false ->
 	    Rest = skip_tab_items(Recs, Tab),
-	    restore_items(Rest, Header, Schema, R)
+	    restore_items(Rest, Header, Schema, Ext, R)
     end;
 
-restore_items([], _Header, _Schema, R) ->
+restore_items([], _Header, _Schema, _Ext, R) ->
     R.
 
 restore_func(Tab, R) ->
@@ -2837,8 +3139,14 @@ restore_func(Tab, R) ->
 where_to_commit(Tab, CsList) ->
     Ram =   [{N, ram_copies} || N <- pick(Tab, ram_copies, CsList, [])],
     Disc =  [{N, disc_copies} || N <- pick(Tab, disc_copies, CsList, [])],
-    DiscO = [{N, disc_only_copies} || N <- pick(Tab, disc_only_copies, CsList, [])],
-    Ram ++ Disc ++ DiscO.
+    DiscO = [{N, disc_only_copies} ||
+		N <- pick(Tab, disc_only_copies, CsList, [])],
+    ExtNodes = [{Alias, Mod, pick(Tab, Alias, CsList, [])} ||
+		   {Alias, Mod} <- get_ext_types()],
+    Ext = lists:foldl(fun({Alias, Mod, Ns}, Acc) ->
+			      [{N, {ext, Alias, Mod}} || N <- Ns] ++ Acc
+		      end, [], ExtNodes),
+    Ram ++ Disc ++ DiscO ++ Ext.
 
 %% Changes of the Meta info of schema itself is not allowed
 restore_schema([{schema, schema, _List} | Schema], R) ->
@@ -2917,7 +3225,13 @@ make_dump_tables([schema | _Tabs]) ->
 make_dump_tables([Tab | Tabs]) ->
     get_tid_ts_and_lock(Tab, read),
     TabDef = get_create_list(Tab),
-    DiscResident =  val({Tab, disc_copies}) ++ val({Tab, disc_only_copies}),
+    DiscResident =
+        val({Tab, disc_copies}) ++
+        val({Tab, disc_only_copies}) ++
+        lists:concat([Ns || {{A,M},Ns} <- val({Tab, external_copies}),
+			    lists:member(
+			      mnesia_lib:semantics({ext,A,M},storage),
+			      [disc_copies, disc_only_copies])]),
     verify([], DiscResident,
 	   {"Only allowed on ram_copies", Tab, DiscResident}),
     [{op, dump_table, unknown, TabDef} | make_dump_tables(Tabs)];
@@ -3337,4 +3651,3 @@ unannounce_im_running([N | Ns]) ->
     unannounce_im_running(Ns);
 unannounce_im_running([]) ->
     ok.
-