迁移调整

db/migrate/20191203124938_add_index_to_poll_answer.rb

@@ -1,17 +1,17 @@
 class AddIndexToPollAnswer < ActiveRecord::Migration[5.2]
   def change
-    # remove_index :poll_votes, :poll_question_id
-    # remove_index :poll_votes, :user_id
-    # remove_index :poll_votes, :poll_answer_id
-    #
-    # change_column_default :poll_votes, :poll_question_id, from: nil, to: -1
-    # PollVote.where(poll_answer_id: nil).update_all(poll_answer_id: -1)
-    #
-    # sql = %Q(delete from poll_votes where (poll_question_id, user_id, poll_answer_id) in
-    #         (select * from (select poll_question_id, user_id, poll_answer_id from poll_votes group by poll_question_id, user_id, poll_answer_id having count(*) > 1) a)
-    #         and id not in (select * from (select min(id) from poll_votes group by poll_question_id, user_id, poll_answer_id having count(*) > 1 order by id) b))
-    # ActiveRecord::Base.connection.execute sql
-    #
-    # add_index :poll_votes, [:poll_question_id, :user_id, :poll_answer_id], name: 'poll_answer_index', unique: true
+    remove_index :poll_votes, :poll_question_id
+    remove_index :poll_votes, :user_id
+    remove_index :poll_votes, :poll_answer_id
+
+    change_column_default :poll_votes, :poll_question_id, from: nil, to: -1
+    PollVote.where(poll_answer_id: nil).update_all(poll_answer_id: -1)
+
+    sql = %Q(delete from poll_votes where (poll_question_id, user_id, poll_answer_id) in
+            (select * from (select poll_question_id, user_id, poll_answer_id from poll_votes group by poll_question_id, user_id, poll_answer_id having count(*) > 1) a)
+            and id not in (select * from (select min(id) from poll_votes group by poll_question_id, user_id, poll_answer_id having count(*) > 1 order by id) b))
+    ActiveRecord::Base.connection.execute sql
+
+    add_index :poll_votes, [:poll_question_id, :user_id, :poll_answer_id], name: 'poll_answer_index', unique: true
   end
 end