ruby-on-rails – Active Record运行所有查询两次

更新这是来自rails控制台：

User.all
  User Load (0.5ms)  SELECT "users".* FROM "users"
  User Load (0.5ms)  SELECT "users".* FROM "users"
2.0.0-p451 :005 > User.first.destroy
  User Load (0.6ms)  SELECT "users".* FROM "users" ORDER BY "users"."id" ASC LIMIT 1
  User Load (0.6ms)  SELECT "users".* FROM "users" ORDER BY "users"."id" ASC LIMIT 1
   (0.2ms)  BEGIN
   (0.2ms)  BEGIN
  Discussion Load (60.4ms)  SELECT DISTINCT "discussions".* FROM "discussions" INNER JOIN "followers" ON "discussions"."id" = "followers"."discussion_id" WHERE "followers"."user_id" = $1  [["user_id",1]]
  Discussion Load (60.4ms)  SELECT DISTINCT "discussions".* FROM "discussions" INNER JOIN "followers" ON "discussions"."id" = "followers"."discussion_id" WHERE "followers"."user_id" = $1  [["user_id",1]]
  Reply Load (0.8ms)  SELECT "replies".* FROM "replies" WHERE "replies"."user_id" = $1  [["user_id",1]]
  SQL (0.4ms)  DELETE FROM "users" WHERE "users"."id" = $1  [["id",1]]
   (0.5ms)  COMMIT
   (0.5ms)  COMMIT

我的制作设置：

config.cache_classes = false
  config.eager_load = false
  config.consider_all_requests_local       = true
  config.action_controller.perform_caching = false
  config.action_mailer.default_url_options = { host: 'xxx' }
  config.action_mailer.raise_delivery_errors = true
  config.action_mailer.delivery_method = :smtp
  config.action_mailer.smtp_settings = {
    :authentication => :plain,:address => "xxx",:port => xxx,:domain => "xxx",:user_name => "xxx",:password => "xxx"
  }


  config.active_support.deprecation = :log
  config.active_record.migration_error = :page_load
  config.serve_static_assets = :false
  config.log_level = :debug
  config.assets.debug = true

希望有一些共同的问题？真不奇怪不是吗？