Andrew Choi 蔡健發 (清心明月), 不務正業的行街

Source: https://stackoverflow.com/questions/2366018/how-to-re-sync-the-mysql-db-if-master-and-slave-have-different-database-incase-o, David Espart 2010

This is the full step-by-step procedure to resync a master-slave replication from scratch:

At the master:

RESET MASTER;
FLUSH TABLES WITH READ LOCK;
SHOW MASTER STATUS;

And copy the values of the result of the last command somewhere.

Without closing the connection to the client (because it would release the read lock) issue the command to get a dump of the master:

mysqldump -u root -p --all-databases > /a/path/mysqldump.sql

Now you can release the lock, even if the dump hasn’t ended yet. To do it, perform the following command in the MySQL client:

UNLOCK TABLES;

Now copy the dump file to the slave using scp or your preferred tool.

At the slave:

Open a connection to mysql and type:

STOP SLAVE;

Load master’s data dump with this console command:

mysql -uroot -p < mysqldump.sql

Sync slave and master logs:

RESET SLAVE;
CHANGE MASTER TO MASTER_LOG_FILE='mysql-bin.000001', MASTER_LOG_POS=98;

Where the values of the above fields are the ones you copied before.

Finally, type:

START SLAVE;

To check that everything is working again, after typing:

SHOW SLAVE STATUS;

you should see:

Slave_IO_Running: Yes
Slave_SQL_Running: Yes

That’s it!

master Server

show master status;

+------------------+----------+--------------+------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+------------------+----------+--------------+------------------+
| mysql-bin.000177 | 31692464 |              |                  |
+------------------+----------+--------------+------------------+
1 row in set (0.000 sec)

File = mysql-bin.000177, Position = 31692464

slave Server

stop slave;
CHANGE MASTER TO master_log_file = 'mysql-bin.000177', master_log_pos =31692464;
start slave;
show slave status \G;

master

show master status;

slave

show slave status \G;