Yes and no When the upgrade does not contain any changes to the mysql database (like new tables etc.) there is no need for the upgrade script to run. But when a minor upgrade contains database changes, it would be neccessary to execute / do the upgrade script. So this is the reason why from 1.9.2 to 1.9.3 there is no upgrade script needed, but not a general valid statement, since it depends on the changes of every (minor/major) update.