Ronald Bradford
MySQL Expert

MySQL Expert Ronald Bradford shares valuable input in MySQL Performance Tuning, MySQL Scalability and general MySQL Help from his two decades of working with MySQL, Oracle, Ingres and development technologies.

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Watching a slave catchup

This neat one line command can be of interest when you are rebuilding a MySQL slave and replication is currently catching up.

$ watch --interval=1 --differences 'mysql -uuser -ppassword -e "show slave status\G"'

You will see the standard SHOW SLAVE STATUS output, but the watch command presents an updated view every second, and highlights differences. This can be useful in a background window to keep an eye on those ‘Seconds Behind Master’.

*************************** 1. row ***************************
             Slave_IO_State: Waiting for master to send event
                Master_Host: 10.10.10.10
                Master_User: slave
                Master_Port: 3306
              Connect_Retry: 60
            Master_Log_File: mysql-bin.000626
        Read_Master_Log_Pos: 88159239
             Relay_Log_File: slave-relay.000005
              Relay_Log_Pos: 426677632
      Relay_Master_Log_File: mysql-bin.000621
           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: 426677495
            Relay_Log_Space: 2714497549
            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: 24131

This entry was posted on Tuesday, February 24th, 2009 at 11:48 am and is filed under Databases, General, Linux, MySQL, Open Source, Professional. You can follow any responses to this entry through the RSS 2.0 feed. You can skip to the end and leave a response. Pinging is currently not allowed.

2 Responses to “Watching a slave catchup”

  1. Darren Cassar says:
    February 24, 2009 at 1:17 pm

    Another solution keeping it to basic commands:

    while [ 1 ]; do mysql -uuser -ppassword -e “show slave status\G” | grep Seconds_Behind_Master; sleep 1; done

  2. Matthew Montgomery says:
    February 24, 2009 at 3:03 pm

    http://day32.com/MySQL/time_behind_master.sh produces the same but in a human readable “2 days 7 hours 15 minutes 37 seconds” time format.

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