As of 5.5 you are no longer required to properly configure the report_host option:

“Displays a list of replication slaves currently registered with the master. (Before MySQL 5.5.3, only slaves started with the –report-host=host_name option are visible in this list.)”

http://dev.mysql.com/doc/refman/5.5/en/show-slave-hosts.html

And.. I feel your pain with replication topology – to do this properly is quite a chore (we jump through a few hoops in MEM to do this as well).

We were lucky enough to have the replication team’s ear however, and 5.6 answers some prayers – each instance has a UUID automatically created for it on startup now, and that is then peppered through SHOW VARIABLES (server_uuid), SHOW SLAVE STATUS (Master_UUID) and SHOW SLAVE HOSTS (Slave_UUID):

http://dev.mysql.com/doc/refman/5.6/en/show-slave-status.html
http://dev.mysql.com/doc/refman/5.6/en/show-slave-hosts.html

You can just walk the uuid chain, assuming you are getting data for all of the servers in the topology. SHOW SLAVE HOSTS can tell you the ones you don’t know about consistently now as well.

Cheers,

Mark