## blah blah blah

mysql> explain SELECT `products`.* FROM `products` INNER JOIN `lines` on `products`.line_id = `lines`.id WHERE (`lines`.gender in ('w')) ORDER BY `products`.orders_count desc LIMIT 0, 12;
+----+-------------+----------+------+------------------------------------------------+--------------------------------------------+---------+------------------------+------+-----------------------------------------------------------+
| id | select_type | table    | type | possible_keys                                  | key                                        | key_len | ref                    | rows | Extra                                                     |
+----+-------------+----------+------+------------------------------------------------+--------------------------------------------+---------+------------------------+------+-----------------------------------------------------------+
|  1 | SIMPLE      | lines    | ref  | PRIMARY,index_lines_on_gender_and_orders_count | index_lines_on_gender_and_orders_count     | 6       | const                  | 1782 | Using where; Using index; Using temporary; Using filesort |
|  1 | SIMPLE      | products | ref  | index_products_on_line_id_and_orders_count     | index_products_on_line_id_and_orders_count | 5       | nuperfume_dev.lines.id |    2 | Using where                                               |
+----+-------------+----------+------+------------------------------------------------+--------------------------------------------+---------+------------------------+------+-----------------------------------------------------------+
2 rows in set (0.00 sec)

mysql> show create table `lines`\G
*************************** 1. row ***************************
       Table: lines
Create Table: CREATE TABLE `lines` (
  `id` int(11) NOT NULL auto_increment,
  `maker_id` varchar(255) default NULL,
  `name` varchar(255) default NULL,
  `gender` varchar(1) default NULL,
  `description` text,
  `introduced` int(11) default NULL,
  `category` varchar(255) default NULL,
  `recommended_use` varchar(255) default NULL,
  `notes` varchar(255) default NULL,
  `character` varchar(255) default NULL,
  `orders_count` int(11) default NULL,
  `popularity` int(11) default NULL,
  `created_at` datetime default NULL,
  `updated_at` datetime default NULL,
  `permalink` varchar(255) default NULL,
  PRIMARY KEY  (`id`),
  KEY `index_lines_on_maker_id` (`maker_id`),
  KEY `index_lines_on_name` (`name`),
  KEY `index_lines_on_permalink_and_gender` (`permalink`,`gender`),
  KEY `index_lines_on_gender_and_orders_count` (`gender`,`orders_count`),
  KEY `index_lines_on_name_and_orders_count` (`name`,`orders_count`),
  KEY `index_lines_on_category` (`category`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8
1 row in set (0.01 sec)

mysql> show create table products\G
*************************** 1. row ***************************
       Table: products
Create Table: CREATE TABLE `products` (
  `id` int(11) NOT NULL auto_increment,
  `line_id` int(11) default NULL,
  `content` varchar(255) default NULL,
  `size` decimal(10,2) default NULL,
  `unit` varchar(8) default NULL,
  `msrp` decimal(10,2) default NULL,
  `price` decimal(10,2) default NULL,
  `quantity` decimal(10,0) default NULL,
  `subcategory` varchar(255) default NULL,
  `info` varchar(255) default NULL,
  `giftset` tinyint(1) default NULL,
  `dirtiness` int(11) default NULL,
  `created_at` datetime default NULL,
  `updated_at` datetime default NULL,
  `nosale` tinyint(1) default '1',
  `orders_count` int(11) default NULL,
  PRIMARY KEY  (`id`),
  KEY `index_products_on_line_id_and_orders_count` (`line_id`,`orders_count`),
  KEY `index_products_on_orders_count` (`orders_count`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8
1 row in set (0.00 sec)