$minId = $dbw->selectField( 'archive', 'MIN(ar_rev_id)', [], __METHOD__ );
$maxId = $dbw->selectField( 'archive', 'MAX(ar_rev_id)', [], __METHOD__ );
$minId = $dbw->selectField( 'archive', 'MIN(ar_rev_id)', [], __METHOD__ );
$maxId = $dbw->selectField( 'archive', 'MAX(ar_rev_id)', [], __METHOD__ );