CREATE TABLE `product_meta` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `product_id` int(11) NOT NULL,
  `meta_key` varchar(50) NOT NULL,
  `meta_value` text NOT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `key` (`meta_key`,`product_id`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1