the finish/disconnect calls ought to be included

Half right. Finish is not the same as disconnect. You remain connected to your backend until you explicitly disconnect (barring network problems, mod_perl, etc) but finish() happens on its own when you retrieve all the data. Read the DBI docs, you only need to call finish() when you execute a query, then disconnect or DESTROY before fully fetching all rows. In the OP's case, he/she does fetch all rows so you were right the first time about finish, there's no reason to call it at the end of this script.