From f75d78d3f564b6253f84ed5e3776c4fa233fdd17 Mon Sep 17 00:00:00 2001
From: Evgeniy Khramtsov <ekhramtsov@process-one.net>
Date: Mon, 22 Jul 2013 10:46:00 +1000
Subject: [PATCH] Make it possible to import without cursor usage

---
 src/ejd2odbc.erl | 60 ++++++++++++++++++++++++++++++------------------
 1 file changed, 38 insertions(+), 22 deletions(-)

diff --git a/src/ejd2odbc.erl b/src/ejd2odbc.erl
index 8777a7597..d178902c0 100644
--- a/src/ejd2odbc.erl
+++ b/src/ejd2odbc.erl
@@ -103,21 +103,24 @@ import_file(Server, FileName) ->
     end.
 
 import(Server, Output) ->
+    import(Server, Output, [{fast, true}]).
+
+import(Server, Output, Opts) ->
     LServer = jlib:nameprep(iolist_to_binary(Server)),
     Modules = modules(),
     IO = prepare_output(Output, disk_log),
     lists:foreach(
       fun(Module) ->
-              import(LServer, IO, Module)
+              import(LServer, IO, Opts, Module)
       end, Modules),
     close_output(Output, IO).
 
-import(Server, Output, Module) ->
+import(Server, Output, Opts, Module) ->
     LServer = jlib:nameprep(iolist_to_binary(Server)),
     IO = prepare_output(Output, disk_log),
     lists:foreach(
       fun({SelectQuery, ConvertFun}) ->
-              import(LServer, SelectQuery, IO, ConvertFun)
+              import(LServer, SelectQuery, IO, ConvertFun, Opts)
       end, Module:import(Server)),
     close_output(Output, IO).
 
@@ -157,31 +160,32 @@ output(_LServer, Table, Fd, SQLs) ->
     file:write(Fd, ["-- \n-- Mnesia table: ", atom_to_list(Table),
                     "\n--\n", SQLs]).
 
-import(LServer, SelectQuery, IO, ConvertFun) ->
-    F = fun() ->
-                ejabberd_odbc:sql_query_t(
-                  iolist_to_binary(
-                    [<<"declare c cursor for ">>, SelectQuery])),
-                fetch(IO, ConvertFun)
+import(LServer, SelectQuery, IO, ConvertFun, Opts) ->
+    F = case proplists:get_bool(fast, Opts) of
+            true ->
+                fun() ->
+                        case ejabberd_odbc:sql_query_t(SelectQuery) of
+                            {selected, _, Rows} ->
+                                lists:foldl(fun process_sql_row/2,
+                                            {IO, ConvertFun, undefined}, Rows);
+                            Err ->
+                                erlang:error(Err)
+                        end
+                end;
+            false ->
+                fun() ->
+                        ejabberd_odbc:sql_query_t(
+                          iolist_to_binary(
+                            [<<"declare c cursor for ">>, SelectQuery])),
+                        fetch(IO, ConvertFun, undefined)
+                end
         end,
     ejabberd_odbc:sql_transaction(LServer, F).
 
-fetch(IO, ConvertFun) ->
-    fetch(IO, ConvertFun, undefined).
-
 fetch(IO, ConvertFun, PrevRow) ->
     case ejabberd_odbc:sql_query_t([<<"fetch c;">>]) of
-        {selected, _, [Row]} when Row == PrevRow ->
-            %% Avoid calling ConvertFun with the same input
-            fetch(IO, ConvertFun, Row);
         {selected, _, [Row]} ->
-            case catch ConvertFun(Row) of
-                {'EXIT', _} = Err ->
-                    ?ERROR_MSG("failed to convert ~p: ~p",
-                               [Row, Err]);
-                Term ->
-                    ok = disk_log:log(IO#dump.fd, Term)
-            end,
+            process_sql_row(Row, {IO, ConvertFun, PrevRow}),
             fetch(IO, ConvertFun, Row);
         {selected, _, []} ->
             ok;
@@ -189,6 +193,18 @@ fetch(IO, ConvertFun, PrevRow) ->
             erlang:error(Err)
     end.
 
+process_sql_row(Row, {IO, ConvertFun, PrevRow}) when Row == PrevRow ->
+    %% Avoid calling ConvertFun with the same input
+    {IO, ConvertFun, Row};
+process_sql_row(Row, {IO, ConvertFun, _PrevRow}) ->
+    case catch ConvertFun(Row) of
+        {'EXIT', _} = Err ->
+            ?ERROR_MSG("failed to convert ~p: ~p", [Row, Err]);
+        Term ->
+            ok = disk_log:log(IO#dump.fd, Term)
+    end,
+    {IO, ConvertFun, Row}.
+
 import_dump(LServer, Mods, #dump{fd = Fd, cont = Cont}) ->
     case disk_log:chunk(Fd, Cont) of
         {NewCont, Terms} ->