diff --git a/src/meta/src/controller/fragment.rs b/src/meta/src/controller/fragment.rs
index f7d0d695452b4..b2d4a0545ae3f 100644
--- a/src/meta/src/controller/fragment.rs
+++ b/src/meta/src/controller/fragment.rs
@@ -728,7 +728,10 @@ impl CatalogController {
                     Expr::col((table::Entity, table::Column::Name)),
                     Expr::if_null(
                         Expr::col((source::Entity, source::Column::Name)),
-                        Expr::col((sink::Entity, sink::Column::Name)),
+                        Expr::if_null(
+                            Expr::col((sink::Entity, sink::Column::Name)),
+                            Expr::val("<unknown>"),
+                        ),
                     ),
                 ),
                 "name",