mysql optimize left join with subquery - mysql

Question

I'm concerned about performance.
It is possibile to optimize the following mysql query?
SELECT u.name, t2.transactions, o2.orders FROM users AS u
LEFT JOIN (
SELECT t.aid AS tuid, SUM( IF( t.status = 1, t.amount, 0 ) ) AS transactions
FROM transactions AS t
WHERE ( t.datetime BETWEEN ('2018-01-01 00:00:00') AND ( '2020-01-01 23:59:59' ) ) GROUP BY t.aid
) AS t2 ON tuid = u.id
LEFT JOIN (
SELECT o.aid AS ouid, SUM(o.net) AS orders FROM orders AS o
WHERE ( o.date BETWEEN ('2018-01-01 00:00:00') AND ( '2020-01-01 23:59:59' ) ) GROUP BY o.aid
) AS o2 ON ouid = u.id
WHERE u.status = 1
ORDER BY t2.transactions DESC
basically I need to sum users' data from multiple tables (and be able to order them)

Answer 1

There's no obvious query-performance antipattern in your query. Performance pretty much depends on the performance of the two subqueries with group by clauses.
Let's take a look at one of them to find some improvements.
SELECT t.aid AS tuid,
SUM( IF( t.status = 1, t.amount, 0 ) ) AS transactions
FROM afs_transactions AS t
WHERE t.datetime BETWEEN '2018-01-01 00:00:00' AND '2020-01-01 23:59:59'
GROUP BY t.aid
This will be OK if you have an index on afs_transactions.datetime.
But the whole subquery can be rewritten
SELECT t.aid AS tuid,
SUM( t.amount ) AS transactions
FROM afs_transactions AS t
WHERE t.datetime BETWEEN '2018-01-01 00:00:00' AND '2020-01-01 23:59:59'
AND t.status = 1
GROUP BY t.aid
This query will take advantage of a compound index on (status, datetime). If you have many rows with status values not equal to 1, and you have the compound index, the rewritten query will be faster.
Pro tip: BETWEEN for datetime values is generally a poor choice, because, well, 59:59. Try using < rather than BETWEEN's <= for the end of the range.
WHERE t.datetime >= '2018-01-01'
AND t.datetime < '2020-01-02' /* notice, it's the day after the range */

Answer 2

Multiple JOIN ( SELECT ... ) used to be a performance killer (pre 5.6). Now it may be a performance problem.
The alternative is
SELECT u.name,
( SELECT ... WHERE ...=u.id ) AS transactions,
( SELECT ... WHERE ...=u.id ) AS orders
FROM users AS u
WHERE u.status = 1
ORDER BY transactions DESC
The first subquery is a correlated subquery and it looks like
( SELECT SUM( IF(status = 1, amount, 0)
FROM transactions
WHERE aid = u.id
AND datetime >= '2018-01-01'
AND datetime < '2018-01-01' + INTERVAL 2 YEAR`
) AS transactions
(The other one is similar.)
Indexes:
users: INDEX(status, name, id) -- "covering"
transactions: INDEX(aid, datetime)
orders: INDEX(aid, date) or INDEX(aid, date, net)