diff --git a/src/mod_private.erl b/src/mod_private.erl
index 2d63faa9c1c..db3175a57f2 100644
--- a/src/mod_private.erl
+++ b/src/mod_private.erl
@@ -74,10 +74,10 @@
 %% gdpr callback
 %%--------------------------------------------------------------------
 
--callback get_all_nss(LUser, LServer) -> NS when
+-callback get_all_nss(LUser, LServer) -> NSs when
     LUser   :: binary(),
     LServer :: binary(),
-    NS      :: binary().
+    NSs      :: [binary()].
 
 -spec get_personal_data(jid:user(), jid:server()) ->
     [{gdpr:data_group(), gdpr:schema(), gdpr:entries()}].
diff --git a/src/mod_private_mysql.erl b/src/mod_private_mysql.erl
index dad88d4ccc9..56eb15ad4cf 100644
--- a/src/mod_private_mysql.erl
+++ b/src/mod_private_mysql.erl
@@ -9,6 +9,8 @@
          multi_get_data/3,
          remove_user/2]).
 
+-export([get_all_nss/2]).
+
 -include("mongoose.hrl").
 -include("jlib.hrl").
 
@@ -52,3 +54,8 @@ select_value({NS, Def}, RowsDict) ->
 remove_user(LUser, LServer) ->
     SLUser = mongoose_rdbms:escape_string(LUser),
     rdbms_queries:del_user_private_storage(LServer, SLUser).
+
+get_all_nss(LUser, LServer) ->
+    {selected, Res} = rdbms_queries:get_all_roster_namespaces(LServer, LUser),
+    Keys = lists:map(fun({R}) -> R end, Res),
+    Keys.
diff --git a/src/mod_private_rdbms.erl b/src/mod_private_rdbms.erl
index 781e390b518..a433ba68927 100644
--- a/src/mod_private_rdbms.erl
+++ b/src/mod_private_rdbms.erl
@@ -78,14 +78,8 @@ get_data(LUser, LServer, NS, Default) ->
     end.
 
 get_all_nss(LUser, LServer) ->
-    SLUser = mongoose_rdbms:escape_string(LUser),
-    lager:error("LUser = ~p\n", [LUser]),
-    lager:error("LServer = ~p\n", [LServer]),
-    {selected, Res} = mongoose_rdbms:sql_query(
-      LServer,
-      [<<"select namespace from private_storage where username=">>, mongoose_rdbms:use_escaped_string(SLUser)]),
+    {selected, Res} = rdbms_queries:get_all_roster_namespaces(LServer, LUser),
     Keys = lists:map(fun({R}) -> R end, Res),
-    lager:error("Keys = ~p\n", [Keys]),
     Keys.
 
 remove_user(LUser, LServer) ->
diff --git a/src/rdbms/rdbms_queries.erl b/src/rdbms/rdbms_queries.erl
index 27e2ab6d496..0fe0cab738b 100644
--- a/src/rdbms/rdbms_queries.erl
+++ b/src/rdbms/rdbms_queries.erl
@@ -67,6 +67,7 @@
          get_subscription_t/3,
          set_private_data/4,
          set_private_data_sql/3,
+         get_all_roster_namespaces/2,
          get_private_data/3,
          multi_get_private_data/3,
          multi_set_private_data/3,
@@ -641,6 +642,12 @@ set_private_data_sql(Username, LXMLNS, SData) ->
                       mongoose_rdbms:use_escaped_string(LXMLNS), ", ",
                       mongoose_rdbms:use_escaped_string(SData), ");"]].
 
+get_all_roster_namespaces(LServer, Username) ->
+    mongoose_rdbms:sql_query(
+      LServer,
+      [<<"select namespace from private_storage where username=">>,
+       mongoose_rdbms:use_escaped_string(Username)]).
+
 get_private_data(LServer, Username, LXMLNS) ->
     mongoose_rdbms:sql_query(
       LServer,