diff --git a/datapipe/meta/sql_meta.py b/datapipe/meta/sql_meta.py
index 7374226e..db03c0bb 100644
--- a/datapipe/meta/sql_meta.py
+++ b/datapipe/meta/sql_meta.py
@@ -234,7 +234,7 @@ def get_existing_idx(self, idx: Optional[IndexDF] = None) -> IndexDF:
                 # Empty index -> empty result
                 return cast(
                     IndexDF,
-                    pd.DataFrame(columns=[column.name for column in self.sql_schema]),  # type: ignore
+                    pd.DataFrame(columns=self.primary_keys),  # type: ignore
                 )
             idx_cols = list(set(idx.columns.tolist()) & set(self.primary_keys))
         else: