Какую СУБД выбрать для высоконагруженного проекта?

SELECT COUNT(DISTINCT `p`.`id`)
  FROM `products` AS `p`
  JOIN `products_to_tag` AS `p2t` ON `p`.`id` = `p2t`.`product_id`
  JOIN `city` AS `c` ON `c`.`id` = `p`.`city_id`
Where
`p`.`publish` = 1
    AND `p2c`.`tag_id` IN (917, 918, 919, 920, 921)
    AND (`c`.`id` = 108 OR `c`.`parent_id` = 108)

SELECT COUNT(`p`.`id`)
  FROM `products` AS `p`
  LEFT JOIN `products_to_tag` AS `p2t` ON `p`.`id` = `p2t`.`product_id`
  LEFT JOIN `city` AS `c` ON `c`.`id` = `p`.`city_id`
Where
`p`.`publish` = 1
    AND `p2c`.`tag_id` IN (917, 918, 919, 920, 921)
    AND (`c`.`id` = 108 OR `c`.`parent_id` = 108)

SELECT COUNT(`p`.`id`)
  FROM `products` AS `p`
  LEFT JOIN `products_to_tag` AS `p2t` ON `p`.`id` = `p2t`.`product_id`
  LEFT JOIN `city` AS `c` ON `c`.`id` = `p`.`city_id`
Where
`p`.`publish` = 1
    AND `p2c`.`tag_id` IN (917, 918, 919, 920, 921)
    AND (`c`.`id` = 108 OR `c`.`parent_id` = 108)
GROUP BY `p`.`id`

SELECT `products_count`.`v`
  FROM `products_to_tag` AS `p2t`
  JOIN (
    SELECT
      `product_id`,
      COUNT(*) as `v`
    FROM `products` AS `p` 
    WHERE `p`.`publish` = 1
    group by `products`.`id`
  ) as products_count 
  on `products_count`.`product_id` = `p2t`.`product_id`
  JOIN `city` AS `c` ON `c`.`id` = `p`.`city_id`
Where
    `p2c`.`tag_id` IN (917, 918, 919, 920, 921)
    AND (`c`.`id` = 108 OR `c`.`parent_id` = 108)