详细说明MySQL5.7不停业务将传统复制变更为GTID复制的示例代码

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  
+----+------+
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:
row in set (0.00 sec)
 
[zejin] 3302>select * from t_users;
+----+------+
  id   name  
+----+------+
  1   hao  
  2   zhou  
+----+------+
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   
+-------------------------------------+-------+
row in set (0.02 sec)
 
 
[zejin] 3302>SHOW STATUS LIKE 'ONGOING_ANONYMOUS_TRANSACTION_COUNT';
+-------------------------------------+-------+
  Variable_name        Value  
+-------------------------------------+-------+
  Ongoing_anonymous_transaction_count   0   
+-------------------------------------+-------+
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                   
+-----------------+----------+--------------+------------------+-------------------+
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  
+-----------------------------------------+
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  
+----+------+
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: 
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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