MySQL - 查找与连接表中的所有行匹配的行

Question

表1:曲目

表2:Wordlist

表3:N:M轨道有单词(跟踪词)

查找包含所有单词的所有曲目.

目前查询如下:

SELECT DISTINCT t.id FROM track as t
Left Join trackwords as tw ON t.id=tw.trackid
Left Join wordlist as wl on wl.id=tw.wordid
WHERE 
wl.trackusecount>0 
group by t.id
HAVING SUM(IF(wl.word IN ('folsom','prison','blues'),1,0)) = 3;

根据EXPLAIN,使用所有索引是必要的:

+----+-------------+-------+--------+-----------------------+---------+---------+----------------+---------+-------------+
| id | select_type | table | type   | possible_keys         | key     | key_len | ref            | rows    | Extra       |
+----+-------------+-------+--------+-----------------------+---------+---------+----------------+---------+-------------+
|  1 | SIMPLE      | t     | index  | PRIMARY               | PRIMARY | 4       | NULL           | 8194507 | Using index | 
|  1 | SIMPLE      | tw    | ref    | wordid,trackid        | trackid | 4       | mbdb.t.id      |       3 | Using where | 
|  1 | SIMPLE      | wl    | eq_ref | PRIMARY,trackusecount | PRIMARY | 4       | mbdb.tw.wordid |       1 | Using where | 
+----+-------------+-------+--------+-----------------------+---------+---------+----------------+---------+-------------+

但查询需要很长时间.有什么建议可以加快查询速度吗？

Answer 1

如果你只是在寻找拥有所有单词的曲目,那么左连接就没有意义了.我假设(trackid,wordid)组合是独一无二的trackwords.

SELECT t.id
  FROM track as t,  trackwords as tw, wordlist as wl
 WHERE t.id=tw.trackid
   AND wl.id=tw.wordid
   AND wl.trackusecount>0 /* not sure what that is - you have it in your query */
   AND wl.word in ('folsom','prison','blues')
 GROUP by t.id
HAVING count(*) = 3

此查询将受益于wordlist(单词),trackwords(trackid,wordid)和track(id)上的索引.