Konfigurasi Multiple Database CodeIgniter

$active_group = 'default';
$active_record = TRUE;

/* KONFIGURASI DATABASE SERVER ORACLE*/
$ocihost     = '192.168.177.103';
$ocitns      = 'tnsoracle';
$ocischema   = 'bW5jX3N1YnNjcmliZQ==';
$ocipassword = 'MTIzNDU2';

$db['default']['hostname'] = '(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST='.$ocihost.')(PORT=1521))';
$db['default']['hostname'] .='(CONNECT_DATA=(SERVICE_NAME = '.$ocitns.')))';
$db['default']['username'] = $ocischema;
$db['default']['password'] = $ocipassword;
$db['default']['database'] = ''; 
$db['default']['dbdriver'] = 'oci8'; 
$db['default']['autoinit'] = TRUE;
$db['default']['db_debug'] = TRUE;
$db['default']['pconnect'] = FALSE;    

/* KONFIGURASI DATABASE MYSQL  */

$db['gammu']['hostname'] = "192.168.177.183";
$db['gammu']['username'] = "gammu";
$db['gammu']['password'] = "gammu";
$db['gammu']['database'] = "smsd";
$db['gammu']['dbdriver'] = "mysql";