https://blog.csdn.net/wanglei_storage/article/details/51776910
   https://blog.csdn.net/lmy86263/article/details/61660922
   http://www.cnblogs.com/zihunqingxin/p/9389060.html
   https://dba.stackexchange.com/questions/147600
   http://blog.itpub.net/4227/viewspace-667394/
   https://www.cnblogs.com/alipayhutu/p/3292031.html
   https://www.cnblogs.com/hehehe886/p/9150418.html