public static function isEqual(Row $row1, Row $row2)
    {
        //same columns
        $cols1 = $row1->getColumns();
        $cols2 = $row2->getColumns();

        $diff1 = array_udiff($cols1, $cols2, array(__CLASS__, 'compareElements'));
        $diff2 = array_udiff($cols2, $cols1, array(__CLASS__, 'compareElements'));

        if ($diff1 != $diff2) {
            return false;
        }

        $dets1 = $row1->getMetadata();
        $dets2 = $row2->getMetadata();

        ksort($dets1);
        ksort($dets2);

        if ($dets1 != $dets2) {
            return false;
        }

        // either both are null
        // or both have a value
        if (!(is_null($row1->getIdSubDataTable())
            && is_null($row2->getIdSubDataTable())
        )
        ) {
            $subtable1 = $row1->getSubtable();
            $subtable2 = $row2->getSubtable();
            if (!DataTable::isEqual($subtable1, $subtable2)) {
                return false;
            }
        }
        return true;
    }