基于GTID的 故障切换

数据库状态

主库1：192.168.1.246:3306  从库1：192.168.1.246:3307  从库2：192.168.1.246:3308  

主库1(root:127.0.0.1:3306) [db3306]> show master status;+------------------+----------+--------------+------------------+-------------------------------------------+| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set                         |+------------------+----------+--------------+------------------+-------------------------------------------+| mysql-bin.000002 |     2464 |              |                  | d023f67f-4a90-11e7-9eff-0800271d97b5:1-12 |+------------------+----------+--------------+------------------+-------------------------------------------+从库1(root:127.0.0.1:3307) [test]> show master status;+------------------+----------+--------------+------------------+-------------------------------------------------------------------------------------+| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set                                                                   |+------------------+----------+--------------+------------------+-------------------------------------------------------------------------------------+| mysql-bin.000008 |     2449 |              |                  | 6e71bd59-4a97-11e7-ad35-0800271d97b5:1-4,d023f67f-4a90-11e7-9eff-0800271d97b5:1-12 |+------------------+----------+--------------+------------------+-------------------------------------------------------------------------------------+从库2(root:127.0.0.1:3308) [test]> show master status;+------------------+----------+--------------+------------------+-----------------------------------------+| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set                       |+------------------+----------+--------------+------------------+-----------------------------------------+| mysql-bin.000008 |      426 |              |                  | d023f67f-4a90-11e7-9eff-0800271d97b5:11 |+------------------+----------+--------------+------------------+-----------------------------------------+此时从库2与主库落后一个事物，并且3307本身做过一些操作产生了自己的GTID--6e71bd59-4a97-11e7-ad35-0800271d97b5:1-4

假设此时主库故障，从库1选为新主库，从库2复制，并不需要从库1产生的GTID--6e71bd59-4a97-11e7-ad35-0800271d97b5:1-4的事物，
操作如下：

(root:127.0.0.1:3308) [test]> reset master ;Query OK, 0 rows affected (0.04 sec)(root:127.0.0.1:3308) [test]> set global gtid_purged='6e71bd59-4a97-11e7-ad35-0800271d97b5:1-4,d023f67f-4a90-11e7-9eff-0800271d97b5:1-11';Query OK, 0 rows affected (0.02 sec)(root:127.0.0.1:3308) [test]> show master status;+------------------+----------+--------------+------------------+-------------------------------------------------------------------------------------+| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set                                                                   |+------------------+----------+--------------+------------------+-------------------------------------------------------------------------------------+| mysql-bin.000008 |      154 |              |                  | 6e71bd59-4a97-11e7-ad35-0800271d97b5:1-4,d023f67f-4a90-11e7-9eff-0800271d97b5:1-11 |+------------------+----------+--------------+------------------+-------------------------------------------------------------------------------------+(root:127.0.0.1:3308) [test]> CHANGE MASTER TO      ->     MASTER_HOST = '192.168.1.246',      ->     MASTER_PORT = 3307,      ->     MASTER_USER = 'repl',      ->     MASTER_PASSWORD = 'repl',      ->     MASTER_AUTO_POSITION = 1;  Query OK, 0 rows affected, 2 warnings (0.02 sec)(root:127.0.0.1:3308) [test]> start slave;Query OK, 0 rows affected (0.01 sec)(root:127.0.0.1:3308) [test]> show slave status\G*************************** 1. row ***************************               Slave_IO_State: Waiting for master to send event                  Master_Host: 192.168.1.246                  Master_User: repl                  Master_Port: 3307                Connect_Retry: 60              Master_Log_File: mysql-bin.000008          Read_Master_Log_Pos: 2449               Relay_Log_File: relay-bin.000002                Relay_Log_Pos: 686        Relay_Master_Log_File: mysql-bin.000008             Slave_IO_Running: Yes            Slave_SQL_Running: Yes              Replicate_Do_DB:           Replicate_Ignore_DB:            Replicate_Do_Table:        Replicate_Ignore_Table:       Replicate_Wild_Do_Table:   Replicate_Wild_Ignore_Table:                    Last_Errno: 0                   Last_Error:                  Skip_Counter: 0          Exec_Master_Log_Pos: 2449              Relay_Log_Space: 927              Until_Condition: None               Until_Log_File:                 Until_Log_Pos: 0           Master_SSL_Allowed: No           Master_SSL_CA_File:            Master_SSL_CA_Path:               Master_SSL_Cert:             Master_SSL_Cipher:                Master_SSL_Key:         Seconds_Behind_Master: 0Master_SSL_Verify_Server_Cert: No                Last_IO_Errno: 0                Last_IO_Error:                Last_SQL_Errno: 0               Last_SQL_Error:   Replicate_Ignore_Server_Ids:              Master_Server_Id: 10153307                  Master_UUID: 6e71bd59-4a97-11e7-ad35-0800271d97b5             Master_Info_File: mysql.slave_master_info                    SQL_Delay: 0          SQL_Remaining_Delay: NULL      Slave_SQL_Running_State: Slave has read all relay log; waiting for more updates           Master_Retry_Count: 86400                  Master_Bind:       Last_IO_Error_Timestamp:      Last_SQL_Error_Timestamp:                Master_SSL_Crl:            Master_SSL_Crlpath:            Retrieved_Gtid_Set: d023f67f-4a90-11e7-9eff-0800271d97b5:12            Executed_Gtid_Set: 6e71bd59-4a97-11e7-ad35-0800271d97b5:1-4,d023f67f-4a90-11e7-9eff-0800271d97b5:1-12                Auto_Position: 1         Replicate_Rewrite_DB:                  Channel_Name:            Master_TLS_Version: 1 row in set (0.00 sec)