我的Sql查询速度很慢60秒，有人有想法要改进吗？

问题描述

| 我的查询很慢。我正在3个桌子之间搜索。 Se_movies = 80000条记录，se_movie_contenttags = 160万条记录，se_movie_descriptiontags -200000条记录 两个简化的查询。 或-慢

SELECT SQL_NO_CACHE  count(movie_id)
FROM se_movies LEFT JOIN se_users ON se_movies.movie_user_id=se_users.user_id
LEFT  JOIN 
( 
  SELECT did,cid,ifnull(cid,did) as uid FROM ( SELECT tag_object_id AS did FROM se_movie_descriptiontags WHERE tag_name IN (\'dog\') ) AS dtag
  LEFT  JOIN (SELECT tag_object_id AS cid FROM se_movie_contenttags WHERE tag_name IN (\'dog\') ) AS ctag
  ON dtag.did=ctag.cid
UNION 
  SELECT did,did) as uid  FROM ( SELECT tag_object_id AS did FROM se_movie_descriptiontags WHERE tag_name IN (\'dog\') ) AS dtag
  RIGHT  JOIN (SELECT tag_object_id AS cid FROM se_movie_contenttags WHERE tag_name IN (\'dog\') ) AS ctag
  ON dtag.did=ctag.cid
)
AS tagobjects ON se_movies.movie_id=tagobjects.uid
WHERE  ( se_movies.movie_title LIKE \'%dog%\') **OR**  (  (cid IS NOT NULL or  did IS NOT NULL) and uid IS NOT NULL )

AND-快速

SELECT SQL_NO_CACHE  count(movie_id)
FROM se_movies LEFT JOIN se_users ON se_movies.movie_user_id=se_users.user_id
LEFT  JOIN 
( 
  SELECT did,did) as uid  FROM ( SELECT tag_object_id AS did FROM se_movie_descriptiontags WHERE tag_name IN (\'dog\') ) AS dtag
  RIGHT  JOIN (SELECT tag_object_id AS cid FROM se_movie_contenttags WHERE tag_name IN (\'dog\') ) AS ctag
  ON dtag.did=ctag.cid
)
AS tagobjects ON se_movies.movie_id=tagobjects.uid
WHERE   ( se_movies.movie_title LIKE \'%dog%\') **AND**  (  (cid IS NOT NULL or  did IS NOT NULL) and uid IS NOT NULL )

每个人一个人

( se_movies.movie_title LIKE \'%dog%\') - around 300
 (cid IS NOT NULL or  did IS NOT NULL) and uid IS NOT NULL - return 595

但是如果其中任何一个人返回50左右或更少，速度很快。 基本上，如果每个标签和电影表标题中的关键字都超过500，则需要60秒 否则为2.3秒。 有没有更好的办法 ？ 我知道你可以在这两个之间做联盟... 和AND其他东西... 搜索标题或（contenttag或desctag） 问题是查询的变化太多... 如果数据在两个不同的表中，这样做是否存在问题？还是要加快速度？ 谢谢。 系统-mysql apache2 php5 ubuntu-亚马逊AWS。 说明 在此处输入链接说明 解决了 SELECT SQL_NO_CACHE计数（movie_id） 从se_movies左加入se_users进入se_movies.movi​​e_user_id = se_users.user_id 内部联接 （SELECT tag_object_id AS movieid FROM se_movie_contenttags WHERE tag_name IN（\'dog \'） 联盟 SELECT tag_object_id AS movieid从se_movie_descriptiontags在哪里tag_name IN（\'dog \'） 联盟 从s_movies中选择s1.movi​​e_id作为movieid作为s1，在s1.movi​​e_title中像\\％dog％\ 联盟 在s2中从se_movies中选择s2.movi​​e_id AS movieid作为s2，在s2.movi​​e_desc中像\'％dog％\' ） AS tagobjects处于se_movies.movi​​e_id = tagobjects.movi​​eid .5秒     

解决方法

如果

se_movie_descriptiontags

和

se_movie_contenttags

包含成对的

(movie_id,tag)

，并且您想包含所有带有特定标签的电影，我将

tagobjects

内嵌视图替换为：

SELECT `tag_object_id` AS `uid` FROM `se_movie_descriptiontags`
WHERE `tag_name` IN (\'dog\')
UNION
SELECT `tag_object_id` FROM `se_movie_contenttags`
WHERE `tag_name` IN (\'dog\')

此查询将返回在

se_movie_descriptiontags

和

se_movie_contenttags

表中的任何一个或两个中都带有标签\'dog \'的电影ID。然后，您可以在主查询中删除

OR ((cid IS NOT NULL OR did IS NOT NULL) AND uid IS NOT NULL)

。 最终的完整查询为：

SELECT SQL_NO_CACHE count(movie_id)
FROM
    se_movies LEFT JOIN
    se_users ON se_movies.movie_user_id=se_users.user_id INNER JOIN 
    ( 
        SELECT `tag_object_id` AS `uid` FROM `se_movie_descriptiontags`
        WHERE `tag_name` IN (\'dog\')
        UNION
        SELECT `tag_object_id` FROM `se_movie_contenttags`
        WHERE `tag_name` IN (\'dog\')
    ) AS tagobjects ON se_movies.movie_id=tagobjects.uid
WHERE (se_movies.movie_title LIKE \'%dog%\')

另外，请注意，单独的

(se_movies.movie_title LIKE \'%dog%\')

是性能杀手，因为无法通过使用

movie_title

列上的索引对其进行优化，并且肯定会引起表扫描。这主要是由于条件以通配符开头的事实。对于这种情况，我建议您研究MySQL的全文本搜索功能。