diff --git a/apps/emqx_durable_storage/src/emqx_ds.erl b/apps/emqx_durable_storage/src/emqx_ds.erl
index 62d6369ea..e7890a3a1 100644
--- a/apps/emqx_durable_storage/src/emqx_ds.erl
+++ b/apps/emqx_durable_storage/src/emqx_ds.erl
@@ -51,6 +51,7 @@
     shard/0,
     shard_id/0,
     topic/0,
+    topic_filter/0,
     time/0
 ]).
 
@@ -69,7 +70,7 @@
     props := map()
 }.
 
--type iterators() :: #{topic() => iterator()}.
+-type iterators() :: #{topic_filter() => iterator()}.
 
 %% Currently, this is the clientid.  We avoid `emqx_types:clientid()' because that can be
 %% an atom, in theory (?).
@@ -79,17 +80,18 @@
 
 -type iterator_id() :: binary().
 
-%%-type session() :: #session{}.
-
 -type message_store_opts() :: #{}.
 
 -type message_stats() :: #{}.
 
 -type message_id() :: binary().
 
-%% Parsed topic:
+%% Parsed topic.
 -type topic() :: list(binary()).
 
+%% Parsed topic filter.
+-type topic_filter() :: list(binary() | '+' | '#' | '').
+
 -type keyspace() :: atom().
 -type shard_id() :: binary().
 -type shard() :: {keyspace(), shard_id()}.
@@ -103,7 +105,7 @@
 -type replay_id() :: binary().
 
 -type replay() :: {
-    _TopicFilter :: topic(),
+    _TopicFilter :: topic_filter(),
     _StartTime :: time()
 }.
 
@@ -197,7 +199,7 @@ session_suspend(_SessionId) ->
     ok.
 
 %% @doc Called when a client subscribes to a topic. Idempotent.
--spec session_add_iterator(session_id(), topic(), _Props :: map()) ->
+-spec session_add_iterator(session_id(), topic_filter(), _Props :: map()) ->
     {ok, iterator(), _IsNew :: boolean()}.
 session_add_iterator(DSSessionId, TopicFilter, Props) ->
     IteratorRefId = {DSSessionId, TopicFilter},
@@ -238,7 +240,7 @@ session_update_iterator(IteratorRef, Props) ->
     ok = mnesia:write(?ITERATOR_REF_TAB, NIteratorRef, write),
     NIteratorRef.
 
--spec session_get_iterator_id(session_id(), topic()) ->
+-spec session_get_iterator_id(session_id(), topic_filter()) ->
     {ok, iterator_id()} | {error, not_found}.
 session_get_iterator_id(DSSessionId, TopicFilter) ->
     IteratorRefId = {DSSessionId, TopicFilter},
@@ -250,7 +252,7 @@ session_get_iterator_id(DSSessionId, TopicFilter) ->
     end.
 
 %% @doc Called when a client unsubscribes from a topic.
--spec session_del_iterator(session_id(), topic()) -> ok.
+-spec session_del_iterator(session_id(), topic_filter()) -> ok.
 session_del_iterator(DSSessionId, TopicFilter) ->
     IteratorRefId = {DSSessionId, TopicFilter},
     transaction(fun() ->
diff --git a/apps/emqx_durable_storage/src/emqx_ds_int.hrl b/apps/emqx_durable_storage/src/emqx_ds_int.hrl
index bca0088b5..162d14b83 100644
--- a/apps/emqx_durable_storage/src/emqx_ds_int.hrl
+++ b/apps/emqx_durable_storage/src/emqx_ds_int.hrl
@@ -31,7 +31,7 @@
 }).
 
 -record(iterator_ref, {
-    ref_id :: {emqx_ds:session_id(), emqx_topic:words()},
+    ref_id :: {emqx_ds:session_id(), emqx_ds:topic_filter()},
     it_id :: emqx_ds:iterator_id(),
     start_time :: emqx_ds:time(),
     props = #{} :: map()
diff --git a/apps/emqx_durable_storage/src/emqx_ds_message_storage_bitmask.erl b/apps/emqx_durable_storage/src/emqx_ds_message_storage_bitmask.erl
index 437cc5b06..7b141b202 100644
--- a/apps/emqx_durable_storage/src/emqx_ds_message_storage_bitmask.erl
+++ b/apps/emqx_durable_storage/src/emqx_ds_message_storage_bitmask.erl
@@ -132,6 +132,7 @@
 %%================================================================================
 
 -type topic() :: emqx_ds:topic().
+-type topic_filter() :: emqx_ds:topic_filter().
 -type time() :: emqx_ds:time().
 
 %% Number of bits
@@ -191,7 +192,7 @@
 
 -record(filter, {
     keymapper :: keymapper(),
-    topic_filter :: emqx_topic:words(),
+    topic_filter :: topic_filter(),
     start_time :: integer(),
     hash_bitfilter :: integer(),
     hash_bitmask :: integer(),
@@ -412,11 +413,11 @@ extract(Key, #keymapper{bitsize = Size}) ->
     <<Bitstring:Size/integer, _MessageID/binary>> = Key,
     Bitstring.
 
--spec compute_bitstring(topic(), time(), keymapper()) -> integer().
-compute_bitstring(Topic, Timestamp, #keymapper{source = Source}) ->
-    compute_bitstring(Topic, Timestamp, Source, 0).
+-spec compute_bitstring(topic_filter(), time(), keymapper()) -> integer().
+compute_bitstring(TopicFilter, Timestamp, #keymapper{source = Source}) ->
+    compute_bitstring(TopicFilter, Timestamp, Source, 0).
 
--spec compute_topic_bitmask(emqx_topic:words(), keymapper()) -> integer().
+-spec compute_topic_bitmask(topic_filter(), keymapper()) -> integer().
 compute_topic_bitmask(TopicFilter, #keymapper{source = Source}) ->
     compute_topic_bitmask(TopicFilter, Source, 0).