diff --git a/src/tree.py b/src/tree.py
index c11832b0f045c4893a51fcb81537ea70d34281f5..77b2b5078b36b822f36ec9bb2966633b02f7895d 100644
--- a/src/tree.py
+++ b/src/tree.py
@@ -70,10 +70,6 @@ def check_export(base, cfg):
     return flag
 
 
-def gen_node_id():
-    return "oceanbase-" + uuid.uuid4().hex
-
-
 class TreeWalker:
     def __init__(self, root, tree_name, title=None, log=None):
         self.name = tree_name
@@ -307,8 +303,7 @@ class TreeWalker:
         config = self.ensure_section_config(section_path)
         for e in config.get("export", []):
             full_name = os.path.join(section_path, e)
-            logger.info(full_name)
             exercise = load_json(full_name)
-            if not exercise.get("exercise_id"):
+            if "exercise_id" not in exercise:
                 exercise["exercise_id"] = uuid.uuid4().hex
-                dump_json(full_name, exercise, exist_ok=True, override=True)
+                dump_json(full_name, exercise, True, True)