在MySQL5.6版本及以上，配置GTID复制，无需再找binlog和POS点，只需要知道master的IP，端口，账号和密码即可，因为同步复制是自动的，MySQL会通过内部机制GTID（Global Transaction ID）自动找点同步。
server_uuid：服务器身份ID，在第一次启动MySQL时，会自动生成一个server_uuid并写入数据目录下的auto.cnf文件里，官方不建议修改。因为server_uuid跟GTID有密切联系，如下：
[root@centos6u8 data]# pwd /mydata/data [root@centos6u8 data]# cat auto.cnf [auto] server-uuid=dec3228f-d685-11e7-b37f-005056879bd7
GTID：全局事务标识符。使用这个功能，每次事务提交都会在binlog里生成一个唯一的标识符，它由UUID和事务ID组成，首次提交的事务ID为1，第二次为2，以此类推。查看binlog如下：
[root@centos6u8 data]# mysqlbinlog -vv mysql-bin.000001 |grep 'GTID_NEXT' SET @@SESSION.GTID_NEXT= 'dec3228f-d685-11e7-b37f-005056879bd7:1'/*!*/; SET @@SESSION.GTID_NEXT= 'dec3228f-d685-11e7-b37f-005056879bd7:2'/*!*/; SET @@SESSION.GTID_NEXT= 'dec3228f-d685-11e7-b37f-005056879bd7:3'/*!*/; SET @@SESSION.GTID_NEXT= 'dec3228f-d685-11e7-b37f-005056879bd7:4'/*!*/; SET @@SESSION.GTID_NEXT= 'AUTOMATIC' /* added by mysqlbinlog */ /*!*/;
开启GTID复制时，slave直接change master to master_auto_position=1即可同步。
配置过程：
1. 在master和slave上同时在my.cnf文件中写入一下内容：
log-bin=mysql-bin binlog_format=row log_slave_updates=1 #开启之后，表示把relay-log里的日志内容再记录到slave本地的binlog里，MySQL5.7之后做了修改 gtid_mode=ON enforce_gtid_consistency=ON
2. 然后在master库上导出数据：
[root@centos6u8 etc]# mysqldump -uroot -p123 -q --single-transaction -R -E --triggers --default-character-set=utf8 --master-data=2 -B -A >/opt/all.sql [root@centos6u8 opt]# scp all.sql 192.168.165.16:/opt/ root@192.168.165.16's password: all.sql 100% 770KB 770.2KB/s 00:00
3. 在slave库上导入：
[root@mysql02 ~]# mysql -uroot -p123< /opt/all.sql
4. 接着进行同步：
mysql> change master to -> master_host = '192.168.165.15', -> master_port = 3308, -> master_user ='rep', -> master_password = '123456', -> master_auto_position = 1; Query OK, 0 rows affected, 2 warnings (0.00 sec)
如果使用了GTID，就不能使用传统的binlog和POS方式，否则会报错。
当然，使用GITD也有相应的局限性：
- GTID同步复制是基于事务的，所以MyISAM表不支持，这可能导致GTID分配给同一个事务。
- 不支持CREATE TABLE ... SELECT语句，因为该语句会被拆分成create table和insert两个事务，并且，如果两个事务被分配了同一个GTID，会导致insert备库被忽略。
测试：
在传统的主从复制中，如果发生主库的操纵在从库找不到对应记录，直接跳过即可，而使用GTID后：
mysql> show slave status\G; *************************** 1. row *************************** Slave_IO_State: Waiting for master to send event Master_Host: 192.168.165.15 Master_User: rep Master_Port: 3308 Connect_Retry: 60 Master_Log_File: mysql-bin.000001 Read_Master_Log_Pos: 1296 Relay_Log_File: mysql02-relay-bin.000002 Relay_Log_Pos: 1244 Relay_Master_Log_File: mysql-bin.000001 Slave_IO_Running: Yes Slave_SQL_Running: No Replicate_Do_DB: Replicate_Ignore_DB: Replicate_Do_Table: Replicate_Ignore_Table: Replicate_Wild_Do_Table: Replicate_Wild_Ignore_Table: Last_Errno: 1032 Last_Error: Could not execute Delete_rows event on table abctest.t1; Can't find record in 't1', Error_code: 1032; handler error HA_ERR_END_OF_FILE; the event's master log mysql-bin.000001, end_log_pos 1265 Skip_Counter: 0 Exec_Master_Log_Pos: 1031 Relay_Log_Space: 1718 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: NULL Master_SSL_Verify_Server_Cert: No Last_IO_Errno: 0 Last_IO_Error: Last_SQL_Errno: 1032 Last_SQL_Error: Could not execute Delete_rows event on table abctest.t1; Can't find record in 't1', Error_code: 1032; handler error HA_ERR_END_OF_FILE; the event's master log mysql-bin.000001, end_log_pos 1265 Replicate_Ignore_Server_Ids: Master_Server_Id: 10 Master_UUID: dec3228f-d685-11e7-b37f-005056879bd7 Master_Info_File: /mydata/data/master.info SQL_Delay: 0 SQL_Remaining_Delay: NULL Slave_SQL_Running_State: Master_Retry_Count: 86400 Master_Bind: Last_IO_Error_Timestamp: Last_SQL_Error_Timestamp: 180117 19:28:04 Master_SSL_Crl: Master_SSL_Crlpath: Retrieved_Gtid_Set: dec3228f-d685-11e7-b37f-005056879bd7:1-5 Executed_Gtid_Set: dcd77b0f-d689-11e7-87b4-005056870053:1, dec3228f-d685-11e7-b37f-005056879bd7:1-4 Auto_Position: 1 Replicate_Rewrite_DB: Channel_Name: Master_TLS_Version: 1 row in set (0.00 sec) ERROR: No query specified
报错如上，如果使用set global sql_slave_skip_counter=1；会产生如下错误：
mysql> set global sql_slave_skip_counter=1; ERROR 1858 (HY000): sql_slave_skip_counter can not be set when the server is running with @@GLOBAL.GTID_MODE = ON. Instead, for each transaction that you want to skip, generate an empty transaction with the same GTID as the transaction
所以，这里想要跳过，就需要把事务ID设置为控制。
在show slave status\G; 中，观察Retrieved_Gtid_Set和Executed_Gtid_Set这两行，第一行表示接收到的事务，第二行表示已经执行完的事务，所以执行dec3228f-d685-11e7-b37f-005056879bd7:1-5这个事务报错了，只需跳过这个事务即可：
mysql> stop slave; Query OK, 0 rows affected, 1 warning (0.00 sec) mysql> SET GTID_NEXT='dec3228f-d685-11e7-b37f-005056879bd7:5'; Query OK, 0 rows affected (0.00 sec) mysql> begin;commit; Query OK, 0 rows affected (0.00 sec) Query OK, 0 rows affected (0.00 sec) mysql> SET GTID_NEXT="AUTOMATIC"; Query OK, 0 rows affected (0.00 sec) mysql> start slave; Query OK, 0 rows affected (0.01 sec)
查看同步状态：
mysql> show slave status\G; *************************** 1. row *************************** Slave_IO_State: Waiting for master to send event Master_Host: 192.168.165.15 Master_User: rep Master_Port: 3308 Connect_Retry: 60 Master_Log_File: mysql-bin.000001 Read_Master_Log_Pos: 1296 Relay_Log_File: mysql02-relay-bin.000003 Relay_Log_Pos: 454 Relay_Master_Log_File: mysql-bin.000001 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: 1296 Relay_Log_Space: 2018 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: 0 Master_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: 10 Master_UUID: dec3228f-d685-11e7-b37f-005056879bd7 Master_Info_File: /mydata/data/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: dec3228f-d685-11e7-b37f-005056879bd7:1-5 Executed_Gtid_Set: dcd77b0f-d689-11e7-87b4-005056870053:1, dec3228f-d685-11e7-b37f-005056879bd7:1-5 Auto_Position: 1 Replicate_Rewrite_DB: Channel_Name: Master_TLS_Version: 1 row in set (0.00 sec) ERROR: No query specified
在MySQL5.7之前，GTID复制模式相对应的参数必须写到my.cnf文件里，并重启主库和备库才能生效，而MySQL5.7之后，支持在线切换GTID复制模式，大大增强系统的可用性。
传统的默认复制切换为GTID复制，（主从库都需要按照如下顺序执行）：
mysql> set global gtid_mode='OFF_PERMISSIVE'; mysql> set global gtid_mode='ON_PERMISSIVE'; mysql> set global enforce_gtid_consistency=ON; mysql> set global gtid_mode='ON';
GTID复制切换为传统的复制，（主从库按照如下顺序执行）
mysql> stop slave; mysql> set global gtid_mode='ON_PERMISSIVE'; mysql> set global gtid_mode='OFF_PERMISSIVE'; mysql> change master to master_auto_position=0; mysql> set global gtid_mode='OFF'; mysql> set global enforce_gtid_consistency=OFF; mysql> start slave;
