mysql主从不同步问题 Error_code: 1236

 

第一种情况，开启GTID，从库与主库不同步。

 1、在从库上查看从的状态

mysql> show slave status G 
*************************** 1. row ***************************
               Slave_IO_State: 
                  Master_Host: 10.120.141.168
                  Master_User: sys_repl
                  Master_Port: 3306
                Connect_Retry: 10
              Master_Log_File: 
          Read_Master_Log_Pos: 4
               Relay_Log_File: mysqld-relay-bin.000001
                Relay_Log_Pos: 4
        。。。。。。。。
                Last_IO_Error: Got fatal error 1236 from master when reading data from binary log: 'The slave is connecting using CHANGE MASTER TO MASTER_AUTO_POSITION = 1, but the master has purged binary logs containing GTIDs that the slave requires.'
        。。。。。。
             Retrieved_Gtid_Set: 79212d47-7122-11e7-8641-0050569f788a:13579-17760
            Executed_Gtid_Set: 07cfd8f2-b30c-11e7-8909-000d3a80115c:1-7,
635227c2-af6c-11e8-a447-5254003471ec:1-297,
66d902a5-b546-11e7-b1d4-000d3a80115c:1-13,
79212d47-7122-11e7-8641-0050569f788a:1-17760,
9d5436f6-7122-11e7-8e0c-0050569f19f6:1-6
                Auto_Position: 1
         Replicate_Rewrite_DB: 
                 Channel_Name: 
           Master_TLS_Version: 
1 row in set (0.00 sec)

结果报1236的错误，再从主库上查看下主库的状态

 mysql> show master status G
*************************** 1. row ***************************
             File: mysql-bin.000480
         Position: 10751
     Binlog_Do_DB: 
 Binlog_Ignore_DB: 
Executed_Gtid_Set: 07cfd8f2-b30c-11e7-8909-000d3a80115c:1-7,
635227c2-af6c-11e8-a447-5254003471ec:1-297,
66d902a5-b546-11e7-b1d4-000d3a80115c:1-13,
79212d47-7122-11e7-8641-0050569f788a:1-17797,
9d5436f6-7122-11e7-8e0c-0050569f19f6:1-6,
ac29dfbf-aa66-11e8-9d1e-5254003471ec:1
1 row in set (0.00 sec)

mysql> show variables like '%gtid_purged%';
+---------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Variable_name | Value                                                                                                                                                                                                                                                           |
+---------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| gtid_purged   | 07cfd8f2-b30c-11e7-8909-000d3a80115c:1-7,
635227c2-af6c-11e8-a447-5254003471ec:1-297,
66d902a5-b546-11e7-b1d4-000d3a80115c:1-13,
79212d47-7122-11e7-8641-0050569f788a:1-15338,
9d5436f6-7122-11e7-8e0c-0050569f19f6:1-6,
ac29dfbf-aa66-11e8-9d1e-5254003471ec:1 |
+---------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

 发现有一个GTID从库还没有跑，主库就把这个GTID purged掉了，由于从库没有业务在跑，属于备份库，所以我索性直接

mysql> stop slave;
mysql> reset master;

mysql> set global gtid_purged = '07cfd8f2-b30c-11e7-8909-000d3a80115c:1-7,
    '> 635227c2-af6c-11e8-a447-5254003471ec:1-297,
    '> 66d902a5-b546-11e7-b1d4-000d3a80115c:1-13,
    '> 79212d47-7122-11e7-8641-0050569f788a:1-15223,
    '> 9d5436f6-7122-11e7-8e0c-0050569f19f6:1-6,
    '> ac29dfbf-aa66-11e8-9d1e-5254003471ec:1'; #主库的gtid_purged#
mysql> change master to master_host='10.120.141.136',master_user='sys_replication',master_password='x!Jkz@SIe',master_port=3306,master_auto_position=1;
mysql> start slave; 
mysql> show slave status G
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 10.120.141.136
                  Master_User: sys_replication
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000480
          Read_Master_Log_Pos: 10272
               Relay_Log_File: mysqld-relay-bin.000034
                Relay_Log_Pos: 10285
        Relay_Master_Log_File: mysql-bin.000480
             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: 10272
              Relay_Log_Space: 10580
              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: 141135
                  Master_UUID: 79212d47-7122-11e7-8641-0050569f788a
             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: 79212d47-7122-11e7-8641-0050569f788a:15224-17793
            Executed_Gtid_Set: 07cfd8f2-b30c-11e7-8909-000d3a80115c:1-7,
635227c2-af6c-11e8-a447-5254003471ec:1-297,
66d902a5-b546-11e7-b1d4-000d3a80115c:1-13,
79212d47-7122-11e7-8641-0050569f788a:1-17793,
9d5436f6-7122-11e7-8e0c-0050569f19f6:1-6,
ac29dfbf-aa66-11e8-9d1e-5254003471ec:1
                Auto_Position: 1
         Replicate_Rewrite_DB: 
                 Channel_Name: 
           Master_TLS_Version: 
1 row in set (0.00 sec)

总结：

从库在开始同步前,主库会依靠GTID来确认从库在开始同步以后, 能够把每一个主库上执行过的事务(包括slave的SQL Thread)都复现一次,最终保持和主库完全一致;
判断方法也很简单,基本基于两个条件:
1.主库不能purge从库还没有execute的事务(即从库的executed_GTID要大于主库的GTID_Purged);
2.主库上的事务号不能低于从库(即从库的executed_GTID的最后一个事务要在主库的executed_GTID的范围之内);

2、 构架为双主（一主一从，且互为主从），业务和应用在主库上跑，从库做备份，基本没有业务和应用。

从库(s)指向主库(m)时连接良好，主库(m)指向从库(s)时报错1236。

mysql> show slave status G  #主库(m)状态
*************************** 1. row ***************************
               Slave_IO_State: 
                  Master_Host: 10.120.141.168
                  Master_User: sys_repl
                  Master_Port: 3306
                Connect_Retry: 10
              Master_Log_File: 
          Read_Master_Log_Pos: 4
               Relay_Log_File: mysqld-relay-bin.000001
                Relay_Log_Pos: 4
        Relay_Master_Log_File: 
             Slave_IO_Running: No
            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: 0
              Relay_Log_Space: 154
              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: 1236
                Last_IO_Error: Got fatal error 1236 from master when reading data from binary log: 'The slave is connecting using CHANGE MASTER TO MASTER_AUTO_POSITION = 1, but the master has purged binary logs containing GTIDs that the slave requires.'
               Last_SQL_Errno: 0
               Last_SQL_Error: 
  Replicate_Ignore_Server_Ids: 
             Master_Server_Id: 141168
                  Master_UUID: 055a9521-4906-11e8-8cdb-0050569f3621
             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: 181119 14:27:58
     Last_SQL_Error_Timestamp: 
               Master_SSL_Crl: 
           Master_SSL_Crlpath: 
           Retrieved_Gtid_Set: 
            Executed_Gtid_Set: 055a9521-4906-11e8-8cdb-0050569f3621:1-164859,
2f7211a3-fba0-11e5-b668-0050569f3621:1-627,
30d4f3f6-b56b-11e7-acf1-000d3a801c2f:1-14,
375942c7-0723-11e6-b55c-0050569f3621:1-16630,
61edd40b-af6c-11e8-a4f6-525400adeb6d:1-5059,
971844d6-d7ca-11e6-8d01-0050569f6058:1-11929269,
d408633e-fb9f-11e5-8de2-0050569f6058:1-1317354
                Auto_Position: 1
         Replicate_Rewrite_DB: 
                 Channel_Name: 
           Master_TLS_Version: 
1 row in set (0.00 sec)

再看从库(s)的gtid_purged

mysql> show variables like '%gtid%purged%'G
*************************** 1. row ***************************
Variable_name: gtid_purged
        Value: 055a9521-4906-11e8-8cdb-0050569f3621:1-157766,
2f7211a3-fba0-11e5-b668-0050569f3621:1-627,
30d4f3f6-b56b-11e7-acf1-000d3a801c2f:1-14,
375942c7-0723-11e6-b55c-0050569f3621:1-16633,
971844d6-d7ca-11e6-8d01-0050569f6058:1-9581086,
d408633e-fb9f-11e5-8de2-0050569f6058:1-1317354
1 row in set (0.00 sec)

发现由于从库(s)的 gtid_purged大于主库(m)的Executed_Gtid  #从库指向主库的结构已经搭建完成，现在是搭建主库指向从库时报错，即当前主是从#

根据之前总结的规则，主库(s)不能purge从库(m)还没有execute的事务(即从库(m)的executed_GTID要大于主库(s)的GTID_Purged)

所以会报1236的错误。由于主库(m)上还有业务和应用在跑，所以不能生硬的reset master，所以只能想办法把execunt gtid追回来，

我的方法是跳过这三个事务（不是唯一解法，如果差的事务号过多，这个办法就很愚蠢，在这个构架下出现这种错误很有可能在从库上有应用执行过事务，

如果从库执行的事务太多，那就要查查原因了） 

stop slave；
set gtid_next='375942c7-0723-11e6-b55c-0050569f3621:16631'; --指定下一个事务执行的版本，即想要跳过的GTID
begin;
commit;  --注入一个空事物
 set gtid_next='375942c7-0723-11e6-b55c-0050569f3621:16632';
begin;
commit; 
 set gtid_next='375942c7-0723-11e6-b55c-0050569f3621:16633';
begin;
commit; 

set gtid_next='AUTOMATIC'; --自动的寻找GTID事务。

start slave; --开始同步

mysql> show slave status G
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 10.120.141.168
                  Master_User: sys_repl
                  Master_Port: 3306
                Connect_Retry: 10
              Master_Log_File: mysql-bin.000026
          Read_Master_Log_Pos: 185245755
               Relay_Log_File: mysqld-relay-bin.000002
                Relay_Log_Pos: 414
        Relay_Master_Log_File: mysql-bin.000026
             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: 185245755
              Relay_Log_Space: 622
              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: 141168
                  Master_UUID: 055a9521-4906-11e8-8cdb-0050569f3621
             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: 
            Executed_Gtid_Set: 055a9521-4906-11e8-8cdb-0050569f3621:1-164859,
2f7211a3-fba0-11e5-b668-0050569f3621:1-627,
30d4f3f6-b56b-11e7-acf1-000d3a801c2f:1-14,
375942c7-0723-11e6-b55c-0050569f3621:1-16633,
61edd40b-af6c-11e8-a4f6-525400adeb6d:1-5059,
971844d6-d7ca-11e6-8d01-0050569f6058:1-11929305,
d408633e-fb9f-11e5-8de2-0050569f6058:1-1317354
                Auto_Position: 1
         Replicate_Rewrite_DB: 
                 Channel_Name: 
           Master_TLS_Version: 
1 row in set (0.00 sec)

 这样就好了。