[ORACLE] Speed improvement of mechanism for limiting query results

SELECT b.* FROM (
   SELECT a.*, ROWNUM AS doctrine_rownum FROM (
      $query
  ) a
) b
WHERE doctrine_rownum BETWEEN $min AND $max

SELECT * FROM (
  SELECT a.*, rownum AS doctrine_rownum FROM {
    $query
  ) a WHERE rownum <= $max
) WHERE doctrine_rownum >= $min

public function modifyLimitQuery($query, $limit, $offset = null)
{
	$limit = (int) $limit;
	$offset = (int) $offset;
	if (preg_match('/^\s*SELECT/i', $query)) {
		if ( ! preg_match('/\sFROM\s/i', $query)) {
			$query .= " FROM dual";
		}
		if ($limit > 0) {
			$max = $offset + $limit;
			$column = '*';
			if ($offset > 0) {
				$min = $offset + 1;
				$query = 'SELECT * FROM (SELECT a.' . $column . ', rownum AS doctrine_rownum FROM (' . 
						 $query . 
						 ') a WHERE rownum <= ' . $max . ') WHERE doctrine_rownum >= ' . $min;
			} else {
				$query = 'SELECT a.'.$column.' FROM (' . $query .') a WHERE ROWNUM <= ' . $max;
			}
		}
	}
	return $query;
}