I am trying to run the following.

mysql > purge binary logs to 'mysqld-relay-bin.000075';
ERROR 1373 (HY000): Target log not found in binlog index

# cat ./mysqld-relay-bin.index 

What can I do to manually clear remove these relay logs.

MariaDB [(none)]> show slave status;
Empty set (0.00 sec)

MariaDB [(none)]> show master status;
| File          | Position  | Binlog_Do_DB | Binlog_Ignore_DB |
| binary.000141 | 487953618 |              |                  |

ls -lrt /var/lib/mysql/logs/
total 4616604
-rw-rw---- 1 mysql mysql        299 Jun  7 15:04 mysqld-relay-bin.000010
-rw-rw---- 1 mysql mysql        299 Jun  7 15:19 mysqld-relay-bin.000011
-rw-rw---- 1 mysql mysql        299 Jun  7 15:21 mysqld-relay-bin.000012
-rw-rw---- 1 mysql mysql        299 Jul 23 01:15 mysqld-relay-bin.000075
-rw-rw---- 1 mysql mysql        299 Jul 23 01:15 mysqld-relay-bin.000076
-rw-rw---- 1 mysql mysql        268 Jul 24 09:17 mysqld-relay-bin.000077

As part of a backup script that I run. I flush logs every night, could that have an effect.

Maser server where the replication logs are piling up.

MariaDB [(none)]> SHOW VARIABLES LIKE 'server_id';  
| Variable_name | Value |
| server_id     | 1000  |
1 row in set (0.00 sec)

MariaDB [(none)]> SHOW VARIABLES LIKE '%relay%';
| Variable_name         | Value                                  |
| max_relay_log_size    | 1073741824                             |
| relay_log             | /srv/mysql/logs/mysqld-relay-bin       |
| relay_log_basename    | /srv/mysql/logs/mysqld-relay-bin       |
| relay_log_index       | /srv/mysql/logs/mysqld-relay-bin.index |
| relay_log_info_file   | relay-log.info                         |
| relay_log_purge       | ON                                     |
| relay_log_recovery    | OFF                                    |
| relay_log_space_limit | 0                                      |
| sync_relay_log        | 10000                                  |
| sync_relay_log_info   | 10000                                  |

Slave that connects to the master.

MariaDB [(none)]> SHOW VARIABLES LIKE 'server_id';
| Variable_name | Value |
| server_id     | 1002  |
1 row in set (0.00 sec)

MariaDB [(none)]>  SHOW SLAVE STATUS\G;
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_User: db.replicator
                  Master_Port: 3306
                Connect_Retry: 10
              Master_Log_File: binary.000141
          Read_Master_Log_Pos: 540479720
               Relay_Log_File: mysqld-relay-bin.000358
                Relay_Log_Pos: 540480005
        Relay_Master_Log_File: binary.000141
             Slave_IO_Running: Yes
            Slave_SQL_Running: Yes
                   Last_Errno: 0
                 Skip_Counter: 0
          Exec_Master_Log_Pos: 540479720
              Relay_Log_Space: 540480344
              Until_Condition: None
                Until_Log_Pos: 0
           Master_SSL_Allowed: No
        Seconds_Behind_Master: 0
Master_SSL_Verify_Server_Cert: No
                Last_IO_Errno: 0
               Last_SQL_Errno: 0
             Master_Server_Id: 1000
                   Using_Gtid: No
                Parallel_Mode: conservative
1 row in set (0.00 sec)

ERROR: No query specified
  • The relay logs necessarily go away on their own. If valid logs are sticking around, please check few things. First, Are the server_id values (SHOW VARIABLES LIKE 'server_id';) distinct across all connected Master(s) and Slave(s)? Seconds, SHOW SLAVE STATUS; -- is replication caught up? Check Seconds_behind_master, plus check SQL and I/O thread. If replication stopped, or is behind, the relay logs are necessary.
    – akumar
    Jul 25, 2017 at 10:01

1 Answer 1


You are mixing up two things: "binlogs" and "relaylogs"

The Master writes to a sequence of binlogs on the Master. These are purged by any of () expire_logs_days, () explicit PURGE, (*) OS delete command (not recommended, but possible).

The Slave receives data from the Master's binlogs and immediately writes the data to a sequence of "relay logs" that live on the Slave. The "IO Thread" does that. Meanwhile, the "SQL thread" is reading the relaylogs and performing the actions. As it finishes a relaylog, it automatically deletes the file. No manual action should ever be needed on the relay logs.

What you did was to try a binlog action on the relaylogs. Don't do that.

Normally, there will be one, occasionally two, relay logs visible on the Slave. Since you are seeing dozens, the Slave must be terribly far behind on replication. This probably means that it is stuck. Perform SHOW SLAVE STATUS; to see why. After fixing the problem, the relay logs will cleanup (as mentioned above).

If you do manage to remove/purge/whatever those relay logs, you will permanently break replication. You will have to rebuild the Slave from scratch. So, do not delete those files. (Unless you are rebuilding the Slave, at which point they are ancient history.)

But it is the Master??

  • Is it a "Dual-Master" setup? That is when each of two servers is both Master and Slave to each other.
  • Or it used to be a Slave, and these logs were not cleaned out?
  • Hmmm... all the logs seem to be "empty" (299 bytes), as if something was mis-configured? Such as...
  • Dual-Master with the same server_id gets the servers into a messy loop.

What's in one of those relaylogs?

  • I am seeing these relay logs on the Master
    – nelaaro
    Jul 27, 2017 at 10:13
  • I added to my answer.
    – Rick James
    Jul 27, 2017 at 22:42

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