It is worth noting that not all attributes may be settable via setAttribute(). For example, PDO::MYSQL_ATTR_MAX_BUFFER_SIZE is only settable in PDO::__construct(). You must pass PDO::MYSQL_ATTR_MAX_BUFFER_SIZE as part of the optional 4th parameter to the constructor. This is detailed in http://bugs.php.net/bug.php?id=38015