需要很长时间才能完成，但希望能够快速提取它收集的信息。
SELECT *
FROM releases
WHERE (artist IN (SELECT artist FROM artist_love WHERE user='Quickinho')
OR
label IN (SELECT label FROM label_love WHERE user='Quickinho')
OR
id IN (SELECT release_id FROM charts_extended WHERE artist IN (SELECT dj FROM dj_love WHERE user='Quickinho'))
OR
id IN (SELECT artist FROM releases WHERE id IN (SELECT release_id FROM charts_extended WHERE user='Quickinho'))
OR
id IN (SELECT label FROM releases WHERE id IN (SELECT release_id FROM charts_extended WHERE user='Quickinho')))
AND
id NOT IN (SELECT release_id FROM charts_extended WHERE user='Quickinho')
ORDER BY date DESC
LIMIT 0,102
答案 0 :(得分：8)
避免任何子选择（虽然未经过测试，请原谅任何拼写错误）
SELECT *
FROM releases
LEFT OUTER JOIN artist_love ON releases.artist = artist_love.artist AND artist_love.user = 'Quickinho'
LEFT OUTER JOIN label_love ON releases.label = label_love.label AND label_love.user = 'Quickinho'
LEFT OUTER JOIN charts_extended ON releases.id = charts_extended.release_id
LEFT OUTER JOIN dj_love ON charts_extended.artist = dj_love.dj AND dj_love.user = 'Quickinho'
LEFT OUTER JOIN releases releases1 ON releases.id = releases1.artist
LEFT OUTER JOIN charts_extended charts_extended1 ON charts_extended1.artist = releases1.id AND charts_extended1.user = 'Quickinho'
LEFT OUTER JOIN releases releases2 ON releases.id = releases2.label
LEFT OUTER JOIN charts_extended charts_extended2 ON charts_extended2.artist = releases2.id AND charts_extended2.user = 'Quickinho'
LEFT OUTER JOIN charts_extended charts_extended3 ON charts_extended3.release_id = releases.id AND charts_extended3.user = 'Quickinho'
WHERE (artist_love.user IS NOT NULL
OR label_love.user IS NOT NULL
OR dj_love.user IS NOT NULL
OR charts_extended1.user IS NOT NULL
OR charts_extended2.user IS NOT NULL)
AND charts_extended3.user IS NULL
答案 1 :(得分：4)
其他人提供的优化查询可能还不够快。
假设您的原始查询执行时间为120秒，最佳优化查询仍需要30秒，但您需要5秒或更长时间的响应时间。你能做什么？
运行由定期执行的 cron作业触发的查询，例如每小时。使用INSERT SELECT这样的查询：
INSERT INTO releases_queried
SELECT -- your query (your original one or one of the optimized ones)
见MySQL Manual INSERT-SELECT。然后你会得到
的结果SELECT * FROM releases_queried
立即在毫秒之内。这是一种众所周知的技术，可以缩短响应时间。如果查询所需的数据始终可用，它的效果很好。
StackOverflow本身有很多复杂的查询没有按要求完成，但是是异步的。每次访问都不会计算徽章，而是由cron计算。
答案 2 :(得分：3)
...from releases
WHERE (artist IN (SELECT artist FROM artist_love WHERE user='Quickinho')
我建议您使用JOIN而不是IN (SELECT..)
您可以执行类似
的操作select r.* from releases r, artist_love al
where r.artist = al.artist and al.user='Quickinho'
答案 3 :(得分：2)
IN（）和NOT IN（）子查询优化不佳
MySQL将子查询作为外部查询中每一行的从属子查询执行。这是MySQL 5.5及更早版本中严重性能问题的常见原因。该查询可能应分别重写为JOIN或LEFT OUTER JOIN。
SELECT *
如果表的架构发生更改，选择带有*通配符的所有列将导致查询的含义和行为发生更改，并可能导致查询检索过多数据。
答案 4 :(得分：1)
首先 - 将JOIN关系中使用的所有字段编入索引。
然后尝试此查询 -
SELECT
r.*
FROM
releases r
LEFT JOIN (SELECT artist FROM artist_love WHERE user='Quickinho') al
ON al.artist = r.artist
LEFT JOIN (SELECT label FROM label_love WHERE user='Quickinho') ll
ON ll.label = r.label
LEFT JOIN (
SELECT release_id FROM charts_extended ce
INNER JOIN (SELECT dj FROM dj_love WHERE user='Quickinho') djl
ON djl.dj = ce.artist
) ce
ON r.id = ce.release_id
LEFT JOIN (
SELECT artist FROM releases r
INNER JOIN (SELECT release_id FROM charts_extended WHERE user='Quickinho') ce
ON r.id = release_id
) r2
ON r2.artist = r.id OR r2.label = r.id
LEFT JOIN (SELECT release_id FROM charts_extended WHERE user='Quickinho') ce2
ON ce2.release_id = r.id
WHERE
(al.artist IS NOT NULL OR ll.label IS NOT NULL OR ce.release_id IS NOT NULL OR r2.id IS NOT NULL)
AND ce2.release_id IS NULL
GROUP BY
r.id
答案 5 :(得分：1)
Kickstart的解决方案是正确的想法（虽然我建议你加入USER，如果可能的话，让“user ='Quickinho'”出现这么多次并不是好的做法），然后考虑添加索引到部分或全部以下字段：
虽然我不能说我能想到你正试图用这个做什么。可能有更好的解决方案。
答案 6 :(得分：1)
您可以搜索key_cache，SQL Partition，performance tuning;
答案 7 :(得分：1)
您可以使用JOIN来提高效果。在JOIN中，RDBMS可以创建一个更适合您的查询的执行计划，不像子查询，它将运行所有查询并加载所有数据以进行处理。