我正在尝试从我的seeds.rb文件中执行这一行:ActiveRecord::Base.connection.execute("UPDATEbairrosSETcreated_at=(SELECTNOW());")我名为“bairros”的表有643k行，一旦它在rakedb:seed命令上到达这个文件，它就会抛出这个错误Mysql2::Error:LostconnectiontoMySQLserverduringquery:UPDATEbairrosSETcreated_at=(SELECTNOW());/home/ubuntu/.rvm/gems/ruby-2.0.0-p195@t