diff --git a/apps/emqx/src/emqx_topic_gbt.erl b/apps/emqx/src/emqx_topic_gbt.erl
index dade70cee..063cba21d 100644
--- a/apps/emqx/src/emqx_topic_gbt.erl
+++ b/apps/emqx/src/emqx_topic_gbt.erl
@@ -29,8 +29,8 @@
 -export([get_topic/1]).
 -export([get_record/2]).
 
--type word() :: binary() | '+' | '#'.
--type key(ID) :: {[word()], {ID}}.
+-type key(ID) :: emqx_trie_search:key(ID).
+-type words() :: emqx_trie_search:words().
 -type match(ID) :: key(ID).
 -type name() :: any().
 
@@ -50,7 +50,7 @@ new(Name) ->
 %% @doc Insert a new entry into the index that associates given topic filter to given
 %% record ID, and attaches arbitrary record to the entry. This allows users to choose
 %% between regular and "materialized" indexes, for example.
--spec insert(emqx_types:topic(), _ID, _Record, name()) -> true.
+-spec insert(emqx_types:topic() | words(), _ID, _Record, name()) -> true.
 insert(Filter, ID, Record, Name) ->
     Tree = gbt(Name),
     Key = key(Filter, ID),
@@ -59,7 +59,7 @@ insert(Filter, ID, Record, Name) ->
 
 %% @doc Delete an entry from the index that associates given topic filter to given
 %% record ID. Deleting non-existing entry is not an error.
--spec delete(emqx_types:topic(), _ID, name()) -> true.
+-spec delete(emqx_types:topic() | words(), _ID, name()) -> true.
 delete(Filter, ID, Name) ->
     Tree = gbt(Name),
     Key = key(Filter, ID),
diff --git a/apps/emqx/src/emqx_topic_index.erl b/apps/emqx/src/emqx_topic_index.erl
index 5db8ce7cc..59dfdfeab 100644
--- a/apps/emqx/src/emqx_topic_index.erl
+++ b/apps/emqx/src/emqx_topic_index.erl
@@ -32,6 +32,7 @@
 
 -type key(ID) :: emqx_trie_search:key(ID).
 -type match(ID) :: key(ID).
+-type words() :: emqx_trie_search:words().
 
 %% @doc Create a new ETS table suitable for topic index.
 %% Usable mostly for testing purposes.
@@ -42,18 +43,18 @@ new() ->
 %% @doc Insert a new entry into the index that associates given topic filter to given
 %% record ID, and attaches arbitrary record to the entry. This allows users to choose
 %% between regular and "materialized" indexes, for example.
--spec insert(emqx_types:topic(), _ID, _Record, ets:table()) -> true.
+-spec insert(emqx_types:topic() | words(), _ID, _Record, ets:table()) -> true.
 insert(Filter, ID, Record, Tab) ->
     Key = make_key(Filter, ID),
     true = ets:insert(Tab, {Key, Record}).
 
 %% @doc Delete an entry from the index that associates given topic filter to given
 %% record ID. Deleting non-existing entry is not an error.
--spec delete(emqx_types:topic(), _ID, ets:table()) -> true.
+-spec delete(emqx_types:topic() | words(), _ID, ets:table()) -> true.
 delete(Filter, ID, Tab) ->
     ets:delete(Tab, make_key(Filter, ID)).
 
--spec make_key(emqx_types:topic(), ID) -> key(ID).
+-spec make_key(emqx_types:topic() | words(), ID) -> key(ID).
 make_key(TopicOrFilter, ID) ->
     emqx_trie_search:make_key(TopicOrFilter, ID).
 
diff --git a/apps/emqx/src/emqx_trie_search.erl b/apps/emqx/src/emqx_trie_search.erl
index b774e1459..c8c088b58 100644
--- a/apps/emqx/src/emqx_trie_search.erl
+++ b/apps/emqx/src/emqx_trie_search.erl
@@ -98,24 +98,24 @@
 
 -module(emqx_trie_search).
 
--export([make_key/2]).
+-export([make_key/2, filter/1]).
 -export([match/2, matches/3, get_id/1, get_topic/1]).
--export_type([key/1, word/0, nextf/0, opts/0]).
+-export_type([key/1, word/0, words/0, nextf/0, opts/0]).
 
 -define(END, '$end_of_table').
 
 -type word() :: binary() | '+' | '#'.
+-type words() :: [word()].
 -type base_key() :: {binary() | [word()], {}}.
 -type key(ID) :: {binary() | [word()], {ID}}.
 -type nextf() :: fun((key(_) | base_key()) -> ?END | key(_)).
 -type opts() :: [unique | return_first].
 
 %% @doc Make a search-key for the given topic.
--spec make_key(emqx_types:topic(), ID) -> key(ID).
+-spec make_key(emqx_types:topic() | words(), ID) -> key(ID).
 make_key(Topic, ID) when is_binary(Topic) ->
-    Words = filter_words(Topic),
-    case emqx_topic:wildcard(Words) of
-        true ->
+    case filter(Topic) of
+        Words when is_list(Words) ->
             %% it's a wildcard
             {Words, {ID}};
         false ->
@@ -123,7 +123,15 @@ make_key(Topic, ID) when is_binary(Topic) ->
             %% because they can be found with direct lookups.
             %% it is also more compact in memory.
             {Topic, {ID}}
-    end.
+    end;
+make_key(Words, ID) when is_list(Words) ->
+    {Words, {ID}}.
+
+%% @doc Parse a topic filter into a list of words. Returns `false` if it's not a filter.
+-spec filter(emqx_types:topic()) -> words() | false.
+filter(Topic) ->
+    Words = filter_words(Topic),
+    emqx_topic:wildcard(Words) andalso Words.
 
 %% @doc Extract record ID from the match.
 -spec get_id(key(ID)) -> ID.
@@ -325,6 +333,7 @@ filter_words(Topic) when is_binary(Topic) ->
     % `match_filter/3` expects.
     [word(W, filter) || W <- emqx_topic:tokens(Topic)].
 
+-spec topic_words(emqx_types:topic()) -> [binary()].
 topic_words(Topic) when is_binary(Topic) ->
     [word(W, topic) || W <- emqx_topic:tokens(Topic)].
 
diff --git a/apps/emqx/test/emqx_topic_index_SUITE.erl b/apps/emqx/test/emqx_topic_index_SUITE.erl
index 08056a16f..9df9743f1 100644
--- a/apps/emqx/test/emqx_topic_index_SUITE.erl
+++ b/apps/emqx/test/emqx_topic_index_SUITE.erl
@@ -57,6 +57,17 @@ t_insert(Config) ->
     ?assertEqual(<<"sensor/#">>, topic(match(M, <<"sensor">>, Tab))),
     ?assertEqual(t_insert_3, id(match(M, <<"sensor">>, Tab))).
 
+t_insert_filter(Config) ->
+    M = get_module(Config),
+    Tab = M:new(),
+    Topic = <<"sensor/+/metric//#">>,
+    true = M:insert(Topic, 1, <<>>, Tab),
+    true = M:insert(emqx_trie_search:filter(Topic), 2, <<>>, Tab),
+    ?assertEqual(
+        [Topic, Topic],
+        [topic(X) || X <- matches(M, <<"sensor/1/metric//2">>, Tab)]
+    ).
+
 t_match(Config) ->
     M = get_module(Config),
     Tab = M:new(),
diff --git a/apps/emqx/test/emqx_trie_search_tests.erl b/apps/emqx/test/emqx_trie_search_tests.erl
index 75994131d..d78347de6 100644
--- a/apps/emqx/test/emqx_trie_search_tests.erl
+++ b/apps/emqx/test/emqx_trie_search_tests.erl
@@ -18,15 +18,30 @@
 
 -include_lib("eunit/include/eunit.hrl").
 
-topic_validation_test() ->
+-import(emqx_trie_search, [filter/1]).
+
+filter_test_() ->
+    [
+        ?_assertEqual(
+            [<<"sensor">>, '+', <<"metric">>, <<>>, '#'],
+            filter(<<"sensor/+/metric//#">>)
+        ),
+        ?_assertEqual(
+            false,
+            filter(<<"sensor/1/metric//42">>)
+        )
+    ].
+
+topic_validation_test_() ->
     NextF = fun(_) -> '$end_of_table' end,
     Call = fun(Topic) ->
         emqx_trie_search:match(Topic, NextF)
     end,
-    ?assertError(badarg, Call(<<"+">>)),
-    ?assertError(badarg, Call(<<"#">>)),
-    ?assertError(badarg, Call(<<"a/+/b">>)),
-    ?assertError(badarg, Call(<<"a/b/#">>)),
-    ?assertEqual(false, Call(<<"a/b/b+">>)),
-    ?assertEqual(false, Call(<<"a/b/c#">>)),
-    ok.
+    [
+        ?_assertError(badarg, Call(<<"+">>)),
+        ?_assertError(badarg, Call(<<"#">>)),
+        ?_assertError(badarg, Call(<<"a/+/b">>)),
+        ?_assertError(badarg, Call(<<"a/b/#">>)),
+        ?_assertEqual(false, Call(<<"a/b/b+">>)),
+        ?_assertEqual(false, Call(<<"a/b/c#">>))
+    ].