a less expensive and reusable method
function get_post_id_by_name( $post_name, $post_type = 'post' )
{
$post_ids = get_posts(array
(
'post_name' => $post_name,
'post_type' => $post_type,
'numberposts' => 1,
'fields' => 'ids'
));
return array_shift( $post_ids );
}