diff --git a/server/src/grpc/storage_service/route.rs b/server/src/grpc/storage_service/route.rs
index c398f87667..6ab1cc011e 100644
--- a/server/src/grpc/storage_service/route.rs
+++ b/server/src/grpc/storage_service/route.rs
@@ -13,6 +13,8 @@ pub async fn handle_route<Q>(
     ctx: &HandlerContext<'_, Q>,
     req: RouteRequest,
 ) -> Result<RouteResponse> {
+    // TODO: the case sensitive mode with quoted is not supported now, all table
+    // name will be converted to lowercase.
     let normalized_metrics = req
         .metrics
         .into_iter()