oci8_result.php's question

[eluser]Unknown[/eluser]
A warning occurred when retrieving data from Oracle.

1. In database config
$db['default']['dbdriver'] = 'oci8';

2. In controller
$this->load->database();
$query = $this->db->get( 'TABLE' );

3. Then a PHP error was encountered
Severity: Notice
Message: Undefined variable: rowcount
Filename: oci8/oci8_result.php
Line Number: 56

Variable $rowcount has no value, is this a bug?