mysql 优化limit写法

-- 优化前，查询10005条，摒弃10000条，留下5条
SELECT
	film_id,
	description 
FROM
	film 
ORDER BY
	title 
	LIMIT 10000, 5;
	
	
-- 优化优化后写法，具体是如何起到优化效果的呢？
SELECT
	film.film_id,
	film.description 
FROM
	film
	INNER JOIN ( SELECT film_id FROM film ORDER BY title LIMIT 10000, 5 ) AS tmp USING ( film_id );