How to order by calculated column in mysql - mysql

Question

It is very slow to order by calculated column. Like this one:
select
`users`.`id`,
`username`,
`about_me`,
(
select
count(*)
from
`interests`
inner join `users_interests` on `interests`.`id` = `users_interests`.`interest_id`
where
`users`.`id` = `users_interests`.`user_id`
and `interest_id` in (1, 2, 4) --this is ids of interests which authenticated user has chosen
) as `interests_count`
from
`users`
order by
`interests_count` desc
So in this query i am ordering users By interests which is best suiting authenticated user. And it is very slow in large data tables. Any ideas what will be alternative and much faster solution. Thanks in advance
EDIT
Users Table
CREATE TABLE `users` (
`id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
`roles_id` bigint(20) unsigned NOT NULL DEFAULT 2,
`username` varchar(100) COLLATE utf8mb4_unicode_ci NOT NULL,
`about_me` varchar(70) COLLATE utf8mb4_unicode_ci DEFAULT NULL,
`email` varchar(100) COLLATE utf8mb4_unicode_ci DEFAULT NULL,
`status` tinyint(1) NOT NULL DEFAULT 0,
`email_verified_at` timestamp NULL DEFAULT NULL,
`password` varchar(191) COLLATE utf8mb4_unicode_ci NOT NULL,
`created_at` timestamp NULL DEFAULT NULL,
`updated_at` timestamp NULL DEFAULT NULL,
PRIMARY KEY (`id`),
UNIQUE KEY `users_username_unique` (`username`),
UNIQUE KEY `users_email_unique` (`email`),
KEY `users_roles_id_foreign` (`roles_id`),
CONSTRAINT `users_roles_id_foreign` FOREIGN KEY (`roles_id`) REFERENCES
`user_roles` (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=50102 DEFAULT CHARSET=utf8mb4
COLLATE=utf8mb4_unicode_ci
Interests Table
CREATE TABLE `interests` (
`id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
`name` varchar(191) COLLATE utf8mb4_unicode_ci NOT NULL,
`interest_category_id` bigint(20) unsigned NOT NULL,
`created_at` timestamp NULL DEFAULT NULL,
`updated_at` timestamp NULL DEFAULT NULL,
PRIMARY KEY (`id`),
KEY `interests_interest_category_id_foreign` (`interest_category_id`),
CONSTRAINT `interests_interest_category_id_foreign` FOREIGN KEY
(`interest_category_id`) REFERENCES `interests_categories` (`id`) ON DELETE
CASCADE
) ENGINE=InnoDB AUTO_INCREMENT=61 DEFAULT CHARSET=utf8mb4
COLLATE=utf8mb4_unicode_ci
Pivot table between Users and Interests
CREATE TABLE `users_interests` (
`id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
`user_id` bigint(20) unsigned NOT NULL,
`interest_id` bigint(20) unsigned NOT NULL,
PRIMARY KEY (`id`),
KEY `users_interests_user_id_foreign` (`user_id`),
KEY `users_interests_interest_id_foreign` (`interest_id`),
CONSTRAINT `users_interests_interest_id_foreign` FOREIGN KEY (`interest_id`) REFERENCES `interests` (`id`) ON DELETE CASCADE,
CONSTRAINT `users_interests_user_id_foreign` FOREIGN KEY (`user_id`) REFERENCES `users` (`id`) ON DELETE CASCADE
) ENGINE=InnoDB AUTO_INCREMENT=251552 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci

Answer 1

Without test data it's difficult to know if this would be faster than your current query, but you might find the use of a Common Table Expression (a.k.a. WITH clause) to be helpful here:
with cteCount AS (select ui.`user_id`,
count(*) as `interests_count`
from `interests` i
inner join `users_interests` ui
on i.`id` = ui.`interest_id`
where ui.`interest_id` in (1, 2, 4))
select u.`id`,
`username`,
`about_me`,
cc.`interests_count`
from `users` u
inner join cteCount cc
on cc.`user_id` = u.`id`
order by
cc.`interests_count` desc
The performance of this query will be affected by the presence or absence of indexes on the appropriate columns. Just glancing at it I'd say you should have the following indexes available:
interests
Index 1: id
users_interests
Index 1: interest_id
users
Index 1: id

Answer 2

Try to directly join and aggregate.
SELECT u.id,
u.username,
u.about_me,
count(ui.interest_id) interests_count
FROM users u
LEFT JOIN users_interests ui
ON ui.user_id = u.id
AND ui.interest_id IN (1, 2, 4)
GROUP BY u.id,
u.username,
u.about_me;
Additionally create an index supporting the aggregation.
CREATE INDEX users_id_username_about_me
ON users
(id,
username,
about_me);