diff --git a/ibis/backends/postgres/__init__.py b/ibis/backends/postgres/__init__.py
index b6a3dff2a5e7b..801514d320c78 100644
--- a/ibis/backends/postgres/__init__.py
+++ b/ibis/backends/postgres/__init__.py
@@ -304,7 +304,7 @@ def _post_connect(self) -> None:
             cur.execute("SET TIMEZONE = UTC")
 
     @property
-    def _session_temp_db(self):
+    def _session_temp_db(self) -> str | None:
         # Postgres doesn't assign the temporary table database until the first
         # temp table is created in a given session.
         # Before that temp table is created, this will return `None`
diff --git a/ibis/backends/risingwave/__init__.py b/ibis/backends/risingwave/__init__.py
index 960ab9522b847..d43ca2b51d16b 100644
--- a/ibis/backends/risingwave/__init__.py
+++ b/ibis/backends/risingwave/__init__.py
@@ -586,3 +586,9 @@ def drop_sink(
         )
         with self._safe_raw_sql(src):
             pass
+
+    @property
+    def _session_temp_db(self) -> str | None:
+        # Return `None`, because RisingWave does not implement temp tables like
+        # Postgres
+        return None