Mysql optimization based on explain

问题

I have the following query that takes a really long time to execute. I need to speed it up, but I'm at a lost as to what technique to use. This is the query:

SELECT 
    `User`.`id`, 
    `User`.`username`, 
    `User`.`password`, 
    `User`.`role`, 
    `User`.`created`, 
    `User`.`modified`, 
    `User`.`email`, 
    `User`.`other_user_id`, 
    `User`.`first_name`, 
    `User`.`last_name`, 
    `User`.`place_id`, 
    `Resume`.`id`, 
    `Resume`.`user_id`, 
    `Resume`.`other_resume_id`, 
    `Resume`.`other_user_id`, 
    `Resume`.`file_extension`, 
    `Resume`.`created`, 
    `Resume`.`modified`, 
    `Resume`.`is_deleted`, 
    `Resume`.`has_file`, 
    `Resume`.`is_stamped`, 
    `Resume`.`is_active` 
FROM 
    `streetofwalls`.`users` AS `User` 
    LEFT JOIN `my_database`.`attempts` AS `Attempt` 
        ON (`Attempt`.`user_id` = `User`.`id` AND `Attempt`.`test_id` != 5) 
    LEFT JOIN `my_database`.`reports` AS `Resume` 
        ON (`Resume`.`user_id` = `User`.`id`) 
WHERE 
    `Attempt`.`test_id` = 8 
    AND `Attempt`.`score` > 60 
    AND `User`.`id` IN (
        SELECT 
            `User1`.`id` 
        FROM 
            `my_database`.`users` AS User1 
            LEFT JOIN `my_database`.`tags_users` AS TagUser 
                ON (`User1`.`id`= `TagUser`.`user_id`) 
            LEFT JOIN `my_database`.`tags` AS Tag 
                ON (`TagUser`.`tag_id`= `Tag`.`id`) 
        WHERE `Tag`.`id` = (8) ) 
    AND `User`.`id` NOT IN (
        SELECT 
            `User1`.`id` 
        FROM 
            `my_database`.`users` AS User1 
            LEFT JOIN `my_database`.`tags_users` AS TagUser 
                ON (`User1`.`id`= `TagUser`.`user_id`) 
            LEFT JOIN `my_database`.`tags` AS Tag 
                ON (`TagUser`.`tag_id`= `Tag`.`id`) 
        WHERE `Tag`.`id` = (3) ) 
    AND `Resume`.`has_file` = 1 
GROUP BY `User`.`id` 
ORDER BY `Attempt`.`score` DESC;

This query generates the following explain:

As you can see, I have several indexes on this query. At the moment only the resume table is not able to be indexed. Is is possible to index this table in the context of this query? Is there some other way to speed this query up that I have not thought of? Its prohibitively slow for its intended function and I'm out of ideas. Thank you to anyone who can help. Please let me know if any other information is needed.

回答1:

try inner join instead of sub-query it is default to guide query without running on data,but may be following the query will help you.

SELECT User.id, User.username, User.password, User.role, User.created, User.modified, User.email, User.other_user_id, User.first_name, User.last_name, User.place_id, Resume.id, Resume.user_id, Resume.other_resume_id, Resume.other_user_id, Resume.file_extension, Resume.created, Resume.modified, Resume.is_deleted, Resume.has_file, Resume.is_stamped, Resume.is_active

FROM streetofwalls.users AS User
LEFT JOIN my_database.attempts AS Attempt ON (Attempt.user_id = User.id AND Attempt.test_id != 5) LEFT JOIN my_database.reports AS Resume ON (Resume.user_id = User.id)

, my_database.users AS User1

LEFT JOIN my_database.tags_users AS TagUser on (User1.id= TagUser.user_id)

LEFT JOIN my_database.tags AS Tag ON (TagUser.tag_id= Tag.id)

WHERE User.id = User1.id AND Attempt.test_id = 8 AND Attempt.score > 60
AND Resume.has_file = 1 AND Tag.id = '8' AND Tag.id != '3' GROUP BY User.id ORDER BY Attempt.score DESC;

来源：https://stackoverflow.com/questions/20248803/mysql-optimization-based-on-explain

标签

mysql

sql

join

indexing

explain