[PDO] Number of rows found by Select

What is the recommended way to find the number of rows found by a SELECT query? PDOStatement::rowCount() doesn't work with MySQL and is a bit of a hack anyway. Doing a COUNT(*) before the SELECT is very hackish - the data could have changed and it's an extra query. What is there that's better than either of these? Is there any way to use COUNT(*) without risking data change, such as inside a transaction? I'm amazed that there is no mysql_num_rows() equivilent, I get the feeling that I'm missing something obvious. I can only presume there is some technical limitation that I'm not appreciating, if anyone can shed some light on this, I'd like to know. I'm new to both PDO and this mailing list, so please be gentle with me. I'm using PDO 1.0RC2, PHP 5.0.5 and MySQL 4.1.15. Rob