Question

I have the following SQL Query:

SELECT 
    upd.*,
    usr.username AS `username`,
    usr.profile_picture AS `profile_picture`
FROM 
    updates AS upd
LEFT JOIN 
    subscribers AS sub ON upd.uid=sub.suid
LEFT JOIN 
    users AS usr ON upd.uid=usr.uid
WHERE 
    upd.deleted='0' && (upd.uid='118697835834' || sub.uid='118697835834')
GROUP BY upd.id
ORDER BY upd.date DESC
LIMIT 0, 15

where i get all user(118697835834) updates, his profile picture from another table using left join and also all his subscription users updates so can i show them in his newsfeed.

However as the updates get more and more so the query takes more time to load… right now using Codeigniter’s Profiler i can see that the query takes 1.3793…

Right now i have created around 18k dummy accounts and subscribed from to me and vice versa so i can test the execution time… the times that i get are tragic considering that i am in localhost…

I also have some indexes where i suppose need more in the users table(username and uid as unique), updates table(update_id as unique and uid as index)

I suppose i am doing something wrong to get so bad results…

EDIT:
Running EXPLAIN EXTENDED result:

Array
(
    [0] => stdClass Object
        (
            [id] => 1
            [select_type] => SIMPLE
            [table] => upd
            [type] => ALL
            [possible_keys] => i2
            [key] => 
            [key_len] => 
            [ref] => 
            [rows] => 22
            [filtered] => 100.00
            [Extra] => Using where; Using temporary; Using filesort
        )

    [1] => stdClass Object
        (
            [id] => 1
            [select_type] => SIMPLE
            [table] => sub
            [type] => ALL
            [possible_keys] => 
            [key] => 
            [key_len] => 
            [ref] => 
            [rows] => 18244
            [filtered] => 100.00
            [Extra] => Using where
        )

    [2] => stdClass Object
        (
            [id] => 1
            [select_type] => SIMPLE
            [table] => usr
            [type] => eq_ref
            [possible_keys] => uid
            [key] => uid
            [key_len] => 8
            [ref] => site.upd.uid
            [rows] => 1
            [filtered] => 100.00
            [Extra] => 
        )

)

EDIT2: SHOW CREATE of Tables
Users table:

CREATE TABLE `users` (
 `id` bigint(20) NOT NULL AUTO_INCREMENT,
 `uid` bigint(20) NOT NULL,
 `username` varchar(20) COLLATE utf8_unicode_ci NOT NULL,
 `email` text CHARACTER SET latin1 NOT NULL,
 `password` text CHARACTER SET latin1 NOT NULL,
 `profile_picture_full` text COLLATE utf8_unicode_ci NOT NULL,
 `profile_picture` text COLLATE utf8_unicode_ci NOT NULL,
 `date_registered` datetime NOT NULL,
 `activated` tinyint(1) NOT NULL,
 `closed` tinyint(1) NOT NULL,
 PRIMARY KEY (`id`),
 UNIQUE KEY `uid` (`uid`),
 UNIQUE KEY `username` (`username`)
) ENGINE=MyISAM AUTO_INCREMENT=23521 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci

Subscribers table:

CREATE TABLE `subscribers` (
 `id` bigint(20) NOT NULL AUTO_INCREMENT,
 `sid` bigint(20) NOT NULL,
 `uid` bigint(20) NOT NULL,
 `suid` bigint(20) NOT NULL,
 `date` datetime NOT NULL,
 PRIMARY KEY (`id`)
) ENGINE=MyISAM AUTO_INCREMENT=18255 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci

Updates table:

CREATE TABLE `updates` (
 `id` int(11) NOT NULL AUTO_INCREMENT,
 `update_id` bigint(19) NOT NULL,
 `uid` bigint(20) NOT NULL,
 `type` text COLLATE utf8_unicode_ci NOT NULL,
 `update` text COLLATE utf8_unicode_ci NOT NULL,
 `date` datetime NOT NULL,
 `total_likes` int(11) NOT NULL,
 `total_comments` int(11) NOT NULL,
 `total_favorites` int(11) NOT NULL,
 `category` bigint(20) NOT NULL,
 `deleted` tinyint(1) NOT NULL,
 `deleted_date` datetime NOT NULL,
 PRIMARY KEY (`id`),
 UNIQUE KEY `i1` (`update_id`),
 KEY `i2` (`uid`),
 KEY `deleted_index` (`deleted`)
) ENGINE=MyISAM AUTO_INCREMENT=23 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci

Answer 1

Try this one (without the GROUP BY):

SELECT 
    upd.*,
    usr.username AS `username`,
    usr.profile_picture AS `profile_picture`
FROM 
        updates AS upd
    LEFT JOIN 
        users AS usr 
            ON  upd.uid = usr.uid
WHERE 
    upd.deleted='0' 
  AND 
    ( upd.uid='118697835834'
   OR EXISTS
      ( SELECT *
        FROM   subscribers AS sub 
        WHERE  upd.uid = sub.suid
          AND  sub.uid = '118697835834'
      )
    )
ORDER BY upd.date DESC
LIMIT 0, 15

---

At least the columns that are used in Joins should be indexed: updates.uid, users.uid and subscribers.suid.

I would also add an index on subscribers.uid.