1.使用前备份
mysqldump -uroot -p fission_statistics room_break_history > room_break_history_20170704.dump
2.pt-osc执行DDL
pt-online-schema-change --user='root' --host='localhost' --ask-pass --alter "CHANGE break_type break_type INT(11) NOT NULL,CHANGE app_id app_id INT(11) NOT NULL,CHANGE room_id room_id INT(11) NOT NULL,CHANGE from_user_id from_user_id INT(11) NOT NULL,CHANGE to_user_id to_user_id INT(11) NOT NULL,CHANGE content_type content_type INT(11) NOT NULL,CHANGE source_message source_message VARCHAR(1536) CHARSET utf8mb4 COLLATE ut









