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 masterport 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。

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