Simplify slow MySQL query - mysql

Question

This query calculates the columns free,plus,score and total based on the COUNT of columns in subquery.
SELECT movie_title,movie_id,MAX(x.free_cnt) as free, MAX(x.plus_cnt) as plus,
(MAX(x.free_cnt) + (MAX(x.plus_cnt)*3)) AS score, (MAX(x.free_cnt) + MAX(x.plus_cnt)) AS total
FROM (
SELECT b.id as movie_id, b.movie_title as movie_title, COUNT(*) AS free_cnt, 0 as plus_cnt
FROM subtitles_request a1
LEFT JOIN movies b on a1.movie_id=b.id
JOIN users c on c.email=a1.email
WHERE c.subsc_status='0'
GROUP BY b.movie_title
UNION ALL
SELECT d.id as movie_id, d.movie_title as movie_title, 0 as free_cnt, COUNT(*) AS plus_cnt
FROM subtitles_request a2
LEFT JOIN movies d on a2.movie_id=d.id
JOIN users e on e.email=a2.email
WHERE e.subsc_status='1'
GROUP BY d.movie_title
) AS x
GROUP BY movie_title
ORDER BY total DESC
LIMIT 10
It is slow performing and i'm wondering is there anyway i can simplify or change the query to speed up performance. I can't calculate the free,plus,score ,total columns outside of query due to being able to order by. Also i may incorporate date.
Anyway to simplify this query?

Answer 1

Try this:
SELECT b.movie_title, x.movie_id, MAX( x.free_cnt ) AS free, MAX( x.plus_cnt ) AS plus,
( MAX( x.free_cnt ) + ( MAX( x.plus_cnt ) * 3 ) ) AS score, ( MAX( x.free_cnt ) + MAX( x.plus_cnt ) ) AS total
FROM ( SELECT a.movie_id,
SUM( IF( c.subsc_status = '0', 1, 0 ) ) AS free_cnt,
SUM( IF( c.subsc_status = '1', 1, 0 ) ) AS plus_cnt
FROM subtitles_request a1
JOIN users c on c.email=a1.email
WHERE c.subsc_status in ('0','1')
GROUP BY a.movie_id
) AS x
LEFT JOIN movies b on x.movie_id = b.id
GROUP BY movie_title, movie_id
ORDER BY total DESC
LIMIT 10
Maybe I've simplified a bit too much. Moreover, I'm not used to grouping on only some of the non-aggregate fields, hence I added movie_id to what is being grouped by and thus changing your query a bit (if two films had the same name, but different ID, then only one of the id's would be returned in your original query, but I guess (being a MySQL newbie, I really don't know) the counts would be for both of them taken together).
HTH,
Set

Answer 2

Well, I have check your the subquery:
SELECT b.id as movie_id, b.movie_title as movie_title, COUNT(*) AS free_cnt, 0 as plus_cnt
FROM subtitles_request a1
LEFT JOIN movies b on a1.movie_id=b.id
JOIN users c on c.email=a1.email
WHERE c.subsc_status='0'
GROUP BY b.movie_title
UNION ALL
SELECT d.id as movie_id, d.movie_title as movie_title, 0 as free_cnt, COUNT(*) AS plus_cnt
FROM subtitles_request a2
LEFT JOIN movies d on a2.movie_id=d.id
JOIN users e on e.email=a2.email
WHERE e.subsc_status='1'
GROUP BY d.movie_title
The statement beside "UNION ALL" can be replaced with one statement with condition at c.subsc_status IN('0','1'). And you can try to use "CASE WHEN" statement at 0 as free_cnt, COUNT(*) AS plus_cnt, just like IFNULL((CASE WHEN e.subsc_status='1' THEN COUNT(*)),0) as free_cnt. It's not a complicated sql statement, I don't think it will take too much time to query. Is there too many datas?
As a matter of fact, I'm also a newer, but I just have some experence about it. Please forgive me if it doesn't work.