I was surprised to find on a customer MySQL server this new syntax for Master_host in SHOW SLAVE STATUS.

mysql> SHOW SLAVE STATUS\G
*************************** 1. row ***************************
               Slave_IO_State: Connecting to master
                  Master_Host: testdb1.xxx.com or 10.XXX.XX.XXX
                  Master_User: repl
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: db1-354215-bin-log.000005
          Read_Master_Log_Pos: 1624
               Relay_Log_File: db2-354214-relay-log.000001
   

Is this a fancy new Percona Server feature? No. It’s operator error.

We read a little further to find.

mysql> SHOW SLAVE STATUS\G
...
             Slave_IO_Running: Connecting

...
                Last_IO_Errno: 2005
                Last_IO_Error:

I’m very glad to announce you that MyXplain is released today.

This project is the result of many weeks of work for my friend Max and I and we are obviously very proud to present it.

Please take a time to browse it and find all the surprises that awaiting you.

We wanted to make an unique place, a gathering place where you can find all you want to know about the most useful MySQL commands.
We started with the explain command because we consider it as one of the most important.
show processlist and show slave status will be the next proposed commands on

One very helpful use of the technique Sheeri described in Remote connections without leaving the mysql shell is making sure that replication is working properly.

According to the MySQL Reference Manual’s section on SHOW SLAVE STATUS Syntax, it shows information corresponding to the slave thread in the slave server. When replication is broken, however, or not working properly due to network issues between master and slave, this information may not be accurate. This has improved over recent releases, but it’s still not perfect.

The question, then, is: how to be 100% sure (or as close as you can get to 100%) that replication is running fine? The answer, as

Or, When MySQL Lies!

When I do a show slave status\G, sometimes mysqld will lie to me and give me a wrong Exec_Master_Log_Pos. Let me explain with a situation from last night.

This is the output of show slave status\G from mysql version 5.0.41-community-log:

mysql> show slave status \G
*************************** 1. row ***************************
                Slave_IO_State: Waiting for master to send event
                   Master_Host: XXX.XXX.XXX.XXX
                   Master_User: replic_username
                   Master_Port: 3306
                 Connect_Retry: 60
               Master_Log_File: mysql-bin.000480
           Read_Master_Log_Pos: 690470773
                Relay_Log_File: db2-relay-bin.000028
                 Relay_Log_Pos: 683977007
      Relay_Master_Log_File: