参考资料:
http://dev.mysql.com/doc/refman/5.6/en/innodb-create-index-overview.html
http://www.mysqlperformanceblog.com/2014/02/26/monitor-alter-table-progress-innodb_file_per_table/
http://www.cnblogs.com/gomysql/p/3776192.html
《MySQL技术内幕--innodb存储引擎第2版》