增加索引

db/migrate/20200311092049_add_index_user_id_challenge_id_for_games.rb

@@ -0,0 +1,9 @@
+class AddIndexUserIdChallengeIdForGames < ActiveRecord::Migration[5.2]
+  def change
+    delete_games = Game.where.not(myshixun_id: Myshixun.all).reorder(nil)
+    puts "delete_games: #{delete_games.pluck(:id)}"
+    delete_games.destroy_all
+
+    add_index :games, [:user_id, :challenge_id], unique: true
+  end
+end