MYSQL::Activate Slave server Again to sync with existing Master::Cluster Dissolve::Windows

Scenario: Activating existing slave again to sync with master server after cluster dissolved task happened in the master servers (group replication Innodb Cluster).

Steps:

1.Stop slave to ensure no process to master server.

mysql> STOP SLAVE;

The STOP SLAVE command in MySQL is used to stop the slave replication process on a slave server in a master-slave replication setup. When executed on the slave server, it halts the replication process and stops the slave from applying any new changes received from the master.

Query OK, 0 rows affected, 1 warning (0.00 sec)

2.Change master command to set the new master server ip and credentials details.

 mysql> CHANGE MASTER TO MASTER_HOST='MASTERDBSERVERIP', MASTER_PORT=3306, MASTER_USER='db_repl',

    ->  MASTER_PASSWORD='Password',MASTER_DELAY = 0,MASTER_AUTO_POSITION=1;

Query OK, 0 rows affected, 1 warning (0.05 sec)

 The CHANGE MASTER TO command in MySQL is used on a slave server in a master-slave replication setup to configure and change the replication settings. It is used to specify the master server's connection details and position from which the slave should start replicating.

3.Then start slave to sync master copy to slave.

mysql> START SLAVE;

Query OK, 0 rows affected (0.00 sec)

The START SLAVE command in MySQL is used to start the replication process on a slave server in a master-slave replication setup. When executed on the slave server, it initiates the connection to the master server and begins replicating the changes received from the master.

4.Check show slave status results.

The SHOW SLAVE STATUS command in MySQL is used to display detailed information about the current status of a slave server in a master-slave replication setup. When executed on the slave server, it provides a comprehensive overview of the slave's replication state and configuration.

mysql> show slave status \G;

*************************** 1. row ***************************

               Slave_IO_State: Waiting for master to send event

                  Master_Host: MASTERDBSERVERIP

                  Master_User: db_repl

                  Master_Port: 3306

                Connect_Retry: 60

              Master_Log_File: MASTERDBSERVERNAME-bin.001763

          Read_Master_Log_Pos: 843694033

               Relay_Log_File: SLAVEDBSERVERNAME-relay-bin.000002

                Relay_Log_Pos: 10832949

        Relay_Master_Log_File: MASTERDBSERVERNAME-bin.001763

             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: 843694033

              Relay_Log_Space: 10833158

              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: 13

                  Master_UUID: 08538d8c-ed98-11ea-852d-005056844240

             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: 08538d8c-ed98-11ea-852d-005056844240:942835-942878

            Executed_Gtid_Set: 08538d8c-ed98-11ea-852d-005056844240:1-942878,

28179efb-72c5-11e4-b496-0050569242d9:1-13995703,

29a42f08-7c8e-11ed-969f-005056846111:1-69949262:70421923-70422753,

329fcb1a-c0dd-11eb-82b1-005056847352:1-66160,

6a6ae23d-183f-11eb-ae83-005056846111:1-114606407:114931406-114935574,

ae4d4435-ecbc-11ea-a835-0050568415e0:1-348529,

d1f71bf8-c0dd-11eb-82b1-005056847352:1-258121803,

d9014b6b-1812-11eb-976b-005056846111:1-292573,

dfc8fe40-336a-11ed-a8ea-005056847352:1-48770981

                Auto_Position: 1

         Replicate_Rewrite_DB:

                 Channel_Name:

           Master_TLS_Version:

       Master_public_key_path:

        Get_master_public_key: 0

            Network_Namespace:

1 row in set (0.00 sec)

Interpret the Output: The SHOW SLAVE STATUS command provides a result set with various columns containing information about the replication status. Some of the important columns and their meanings include:

1. Slave_IO_State: The current state of the slave I/O thread.
2. Master_Host and Master_Port: The hostname and port of the master server.
3. Slave_IO_Running and Slave_SQL_Running: Whether the slave I/O thread and slave SQL thread are running (Yes) or stopped (No).
4. Seconds_Behind_Master: The replication lag in seconds, indicating how far behind the slave is compared to the master.
5. Last_Error: Any error message related to replication.
6. Master_Log_File and Read_Master_Log_Pos: The binary log file and position from which the slave is currently reading.
7. Relay_Log_File and Relay_Log_Pos: The relay log file and position, indicating the last processed event on the slave.
8. Exec_Master_Log_Pos: The position of the last executed event on the slave.

These columns provide insights into the replication status, lag, error messages, and positions within the replication process.