diff --git a/db/migrate/20190613022158_add_exec_time_to_challenge.rb b/db/migrate/20190613022158_add_exec_time_to_challenge.rb
index c1743674c..8998b3d82 100644
--- a/db/migrate/20190613022158_add_exec_time_to_challenge.rb
+++ b/db/migrate/20190613022158_add_exec_time_to_challenge.rb
@@ -1,6 +1,6 @@
 class AddExecTimeToChallenge < ActiveRecord::Migration[5.2]
   def change
-    add_column :challenges, :exec_time, :integer
+    # add_column :challenges, :exec_time, :integer
 
     Shixun.find_each do |shixun|
       shixun.challenges.update_all(exec_time: shixun.exec_time)