2 files changed, 7 insertions, 2 deletions
diff --git a/changelog.d/5713.misc b/changelog.d/5713.misc
new file mode 100644
index 0000000000..01ea1cf8d7
--- /dev/null
+++ b/changelog.d/5713.misc
@@ -0,0 +1 @@
+Improve caching when fetching `get_filtered_current_state_ids`.
diff --git a/synapse/storage/state.py b/synapse/storage/state.py
index 0bfe1b4550..a35289876d 100644
--- a/synapse/storage/state.py
+++ b/synapse/storage/state.py
@@ -510,6 +510,12 @@ class StateGroupWorkerStore(EventsWorkerStore, SQLBaseStore):
             event ID.
         """
 
+        where_clause, where_args = state_filter.make_sql_filter_clause()
+
+        if not where_clause:
+            # We delegate to the cached version
+            return self.get_current_state_ids(room_id)
+
         def _get_filtered_current_state_ids_txn(txn):
             results = {}
             sql = """
@@ -517,8 +523,6 @@ class StateGroupWorkerStore(EventsWorkerStore, SQLBaseStore):
                 WHERE room_id = ?
             """
 
-            where_clause, where_args = state_filter.make_sql_filter_clause()
-
             if where_clause:
                 sql += " AND (%s)" % (where_clause,)