php - 此 Mysql SQL Select 查询执行需要 33 分钟

Question

标题说明了一切。你认为有人可以帮我解决这个问题吗？或者是否有人可以指出我还有什么可能导致花费如此多的时间。查询运行大约需要半个小时。写这篇文章的人尝试在循环中执行此操作，方法是从最后一个连接语句中删除表，然后查询每次投票的 field.title 。我希望将结果缩短到 5 分钟左右。

一些额外信息:

查询结果为83,531行

投票表大小为 30 MB(261,169 行)

SELECT `vote`.`id` `vote_id`, `branch`.`name` `branch`, `brand`.`name` `brand`, DATE(vote.created_at) `date`, HOUR(vote.created_at) `time_hour`,
            MINUTE(vote.created_at) `time_minute`, `vote`.`is_like`, `voter`.`name`, `voter`.`telephone`, `voter`.`email`, popups_votes.title  `popup_title`,
            popups_votes.value  `popup_value`, GROUP_CONCAT(dis.field SEPARATOR '|') `reasons`
            FROM (`vote`)
            LEFT JOIN `voter` ON `voter`.`id` = `vote`.`voter_id`
            LEFT JOIN `device` ON `device`.`id` = `vote`.`device_id`
            LEFT JOIN `branch` ON `branch`.`id` = `device`.`branch_id`
            LEFT JOIN `brand` ON `brand`.`id` = `branch`.`brand_id`
            LEFT JOIN `popups_votes` ON popups_votes.vote_id = vote.id
            LEFT JOIN (SELECT vote_dislike.vote_id `vote_id`, field.title `field` FROM vote_dislike
                    LEFT JOIN branch_dislike_field ON branch_dislike_field.id = vote_dislike.branch_dislike_id
                    LEFT JOIN field ON field.id = branch_dislike_field.field_id) dis
                    ON dis.vote_id = vote.id
            WHERE (vote.device_id in
             (
             Select d.id
             From device d
             WHERE d.branch_id IN (SELECT id FROM branch WHERE brand_id = 7)
             )
             )
             AND (vote.created_at >= FROM_UNIXTIME('$from_time') AND vote.created_at <= FROM_UNIXTIME('$to_time') )
            GROUP BY vote.id

编辑:这是解释 {query} 输出:

+------+-------------+----------------------+--------+----------------------+-----------+---------+-------------------------------------------+------+----------------------------------------------+
| id   | select_type | table                | type   | possible_keys        | key       | key_len | ref                                       | rows | Extra                                        |
+------+-------------+----------------------+--------+----------------------+-----------+---------+-------------------------------------------+------+----------------------------------------------+
|    1 | PRIMARY     | branch               | ref    | PRIMARY,brand_id     | brand_id  | 4       | const                                     |   20 | Using index; Using temporary; Using filesort |
|    1 | PRIMARY     | d                    | ref    | PRIMARY,branch_id    | branch_id | 4       | river_back.branch.id                      |    1 | Using index                                  |
|    1 | PRIMARY     | vote                 | ref    | device_id,created_at | device_id | 4       | river_back.d.id                           | 1200 | Using where                                  |
|    1 | PRIMARY     | voter                | eq_ref | PRIMARY              | PRIMARY   | 4       | river_back.vote.voter_id                  |    1 |                                              |
|    1 | PRIMARY     | device               | eq_ref | PRIMARY              | PRIMARY   | 4       | river_back.d.id                           |    1 |                                              |
|    1 | PRIMARY     | branch               | eq_ref | PRIMARY              | PRIMARY   | 4       | river_back.device.branch_id               |    1 | Using where                                  |
|    1 | PRIMARY     | brand                | eq_ref | PRIMARY              | PRIMARY   | 4       | river_back.branch.brand_id                |    1 | Using where                                  |
|    1 | PRIMARY     | popups_votes         | ref    | vote_id              | vote_id   | 5       | river_back.vote.id                        |  602 |                                              |
|    1 | PRIMARY     | vote_dislike         | ref    | vote_id              | vote_id   | 4       | river_back.vote.id                        |    1 |                                              |
|    1 | PRIMARY     | branch_dislike_field | eq_ref | PRIMARY              | PRIMARY   | 4       | river_back.vote_dislike.branch_dislike_id |    1 | Using where                                  |
|    1 | PRIMARY     | field                | eq_ref | PRIMARY              | PRIMARY   | 4       | river_back.branch_dislike_field.field_id  |    1 | Using where                                  |
+------+-------------+----------------------+--------+----------------------+-----------+---------+-------------------------------------------+------+----------------------------------------------+

Answer 1

您应该检查您选择的所有数据是否都已编入索引并且您有外键。

How do MySQL indexes work?

Basically an index on a table works like an index in a book (that's where the name came from):

Let's say you have a book about databases and you want to find some information about, say, storage. Without an index (assuming no other aid, such as a table of contents) you'd have to go through the pages one by one, until you found the topic (that's a full table scan). On the other hand, an index has a list of keywords, so you'd consult the index and see that storage is mentioned on pages 113-120,231 and 354. Then you could flip to those pages directly, without searching (that's a search with an index, somewhat faster).

Basics of Foreign Keys in MySQL?

FOREIGN KEYS just ensure your data are consistent.

They do not improve queries in sense of efficiency, they just make some wrong queries fail.