MySQL5.7不停业务将传统复制变更为GTID复制
由于GTID的优势，我们需要将传统基于file-pos的复制更改为基于GTID的复制，如何在线变更成为我们关心的一个点，如下为具体的方法：
目前我们有一个传统复制下的M-S结构：
port 3301 master
port 3302 slave
master上（3301）： [zejin] 3301>select * from t_users; +----+------+ | id | name | +----+------+ | 1 | hao | | 2 | zhou | +----+------+ 2 rows in set (0.00 sec) slave上（3302）： [zejin] 3302>show slave status\G *************************** 1. row *************************** Slave_IO_State: Waiting for master to send event Master_Host: 192.168.1.240 Master_User: repl Master_Port: 3301 Connect_Retry: 60 Master_Log_File: binlog57.000002 Read_Master_Log_Pos: 417 Relay_Log_File: zejin240-relay-bin.000004 Relay_Log_Pos: 628 Relay_Master_Log_File: binlog57.000002 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: 417 Relay_Log_Space: 884 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: 3301 Master_UUID: a97983fc-5a29-11e6-9d28-000c29d4dc3f Master_Info_File: /home/mysql/I3302/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: Executed_Gtid_Set: Auto_Position: 0 Replicate_Rewrite_DB: Channel_Name: Master_TLS_Version: 1 row in set (0.00 sec) [zejin] 3302>select * from t_users; +----+------+ | id | name | +----+------+ | 1 | hao | | 2 | zhou | +----+------+ 2 rows in set (0.00 sec)
如下为在线变更的具体的操作步骤：
前提：
1.要求所有的mysql版本5.7.6或更高的版本。
2.目前拓扑结构中所有的mysql的gtid_mode的值为off状态。
3.如下的操作步骤都是有序的，不要跳跃着进行。
补充一下全局系统变量GTID_MODE变量值说明：
OFF 新事务是非GTID, Slave只接受不带GTID的事务，传送来GTID的事务会报错
OFF_PERMISSIVE 新事务是非GTID, Slave即接受不带GTID的事务也接受带GTID的事务
ON_PERMISSIVE 新事务是GTID, Slave即接受不带GTID的事务也接受带GTID的事务
ON 新事务是GTID, Slave只接受带GTID的事务
需要注意的是，这几个值的改变是有顺序的，即
off<--->OFF_PERMISSIVE<--->ON_PERMISSIVE<--->ON
不能跳跃执行，会报错。
step1:在每个mysql实例上，将ENFORCE_GTID_CONSISTENCY设置为warning，哪台先执行不影响结果。
[zejin] 3302>set @@global.enforce_gtid_consistency=warn; Query OK, 0 rows affected (0.00 sec) [zejin] 3301>set @@global.enforce_gtid_consistency=warn; Query OK, 0 rows affected (0.00 sec)
注意：执行完这条语句后，如果出现GTID不兼容的语句用法，在错误日志会记录相关信息，那么需要调整应该程序避免不兼容的写法，直到完全没有产生不兼容的语句，可以通过应该程序去排查所有的sql，也可以设置后观察错误日志一段时间，这一步非常重要。
step2：在每个mysql实例上，设置ENFORCE_GTID_CONSISTENCY为ON,哪台先执行不影响结果
在第一步完成后，就可以将值设置为on。
[zejin] 3301>set @@global.enforce_gtid_consistency=on; Query OK, 0 rows affected (0.03 sec) [zejin] 3302>set @@global.enforce_gtid_consistency=on; Query OK, 0 rows affected (0.00 sec)
step3:在每个mysql实例上，设置GTID_MODE为off_permissiv;哪台先执行不影响结果
[zejin] 3301>SET @@GLOBAL.GTID_MODE = OFF_PERMISSIVE; Query OK, 0 rows affected (0.00 sec) [zejin] 3302>SET @@GLOBAL.GTID_MODE = OFF_PERMISSIVE; Query OK, 0 rows affected (0.00 sec)
step4:在每个mysql实例上，设置GTID_MODE为on_permissiv;;哪台先执行不影响结果
[zejin] 3302>SET @@GLOBAL.GTID_MODE = on_permissive; Query OK, 0 rows affected (0.00 sec) [zejin] 3301>SET @@GLOBAL.GTID_MODE = on_permissive; Query OK, 0 rows affected (0.01 sec)
step5:在每个mysql实例上检查变量ONGOING_ANONYMOUS_TRANSACTION_COUNT
[zejin] 3301>SHOW STATUS LIKE 'ONGOING_ANONYMOUS_TRANSACTION_COUNT'; +-------------------------------------+-------+ | Variable_name | Value | +-------------------------------------+-------+ | Ongoing_anonymous_transaction_count | 0 | +-------------------------------------+-------+ 1 row in set (0.02 sec) [zejin] 3302>SHOW STATUS LIKE 'ONGOING_ANONYMOUS_TRANSACTION_COUNT'; +-------------------------------------+-------+ | Variable_name | Value | +-------------------------------------+-------+ | Ongoing_anonymous_transaction_count | 0 | +-------------------------------------+-------+ 1 row in set (0.02 sec)
需要等到此变量为0
step6:确保所有的匿名事务（非GTID事务）已经被完全复制到所有的server上。
检查方法：
在master上： [zejin] 3301>show master status; +-----------------+----------+--------------+------------------+-------------------+ | File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set | +-----------------+----------+--------------+------------------+-------------------+ | binlog57.000005 | 154 | | | | +-----------------+----------+--------------+------------------+-------------------+ 1 row in set (0.00 sec) 在slave上， [zejin] 3302>show slave status\G *************************** 1. row *************************** …… Relay_Master_Log_File: binlog57.000005 Exec_Master_Log_Pos: 154 ……
检查这两项Relay_Master_Log_File的值大于binlog57.000005，
或者等于Relay_Master_Log_File等于binlog57.000005并且Exec_Master_Log_Pos的值大于等于154即可
或者slave直接用函数：
[zejin] 3302>SELECT MASTER_POS_WAIT('binlog57.000005', 154); +-----------------------------------------+ | MASTER_POS_WAIT('binlog57.000005', 154) | +-----------------------------------------+ | 0 | +-----------------------------------------+ 1 row in set (0.00 sec)
返回结果大于等于0就说明匿名事务已经全部复制完成
step7:确认整个拓扑结构中已经没有匿名事务的存在，如之前产生的所有匿名事务已经全部被执行完毕，甚至二进制日志中也不要有匿名事务，可以通过flush logs，并让mysql来自动清理旧的二进制日志文件。
step8:在每个mysql实例上，设置GTID_MODE为on，
[zejin] 3301>SET @@GLOBAL.GTID_MODE = ON; Query OK, 0 rows affected (0.04 sec) [zejin] 3302>SET @@GLOBAL.GTID_MODE = ON; Query OK, 0 rows affected (0.04 sec)
step9:
在每个mysql实例的配置文件my.cnf上，增加gtid-mode=ON
验证：
[zejin] 3301>insert into t_users values(3,'chen'); Query OK, 1 row affected (0.02 sec) [zejin] 3301>update t_users set name='li' where id=1; Query OK, 1 row affected (0.03 sec) Rows matched: 1 Changed: 1 Warnings: 0 [zejin] 3301>select * from t_users; +----+------+ | id | name | +----+------+ | 1 | li | | 2 | zhou | | 3 | chen | +----+------+ 3 rows in set (0.00 sec) [zejin] 3302>show slave status\G *************************** 1. row *************************** Slave_IO_State: Waiting for master to send event Master_Host: 192.168.1.240 Master_User: repl Master_Port: 3301 Connect_Retry: 60 Master_Log_File: binlog57.000006 Read_Master_Log_Pos: 462 Relay_Log_File: zejin240-relay-bin.000012 Relay_Log_Pos: 673 Relay_Master_Log_File: binlog57.000006 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: 462 Relay_Log_Space: 969 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: 3301 Master_UUID: a97983fc-5a29-11e6-9d28-000c29d4dc3f Master_Info_File: /home/mysql/I3302/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: a97983fc-5a29-11e6-9d28-000c29d4dc3f:1-2 Executed_Gtid_Set: a97983fc-5a29-11e6-9d28-000c29d4dc3f:1-2 Auto_Position: 0 Replicate_Rewrite_DB: Channel_Name: Master_TLS_Version: 1 row in set (0.00 sec)
至此完成从传统复制到GTID复制的在线转换。
