标签云与mysql

Question

是否有任何其他方式来从MySQL没有临时表制作标签云？

mysql> explain wallpaper_keywords; 
+--------------+-----------------------+------+-----+---------+----------------+ 
| Field  | Type     | Null | Key | Default | Extra   | 
+--------------+-----------------------+------+-----+---------+----------------+ 
| id   | mediumint(7) unsigned | NO | PRI | NULL | auto_increment | 
| wallpaper_id | mediumint(7) unsigned | YES | MUL | NULL |    | 
| keyword_id | smallint(5) unsigned | YES | MUL | NULL |    | 
+--------------+-----------------------+------+-----+---------+----------------+ 

mysql> explain keywords; 
+---------+-----------------------+------+-----+---------+----------------+ 
| Field | Type     | Null | Key | Default | Extra   | 
+---------+-----------------------+------+-----+---------+----------------+ 
| id  | mediumint(7) unsigned | NO | PRI | NULL | auto_increment | 
| keyword | varchar(32)   | YES | UNI | NULL |    | 
+---------+-----------------------+------+-----+---------+----------------+ 

SELECT k.keyword,count(k.keyword) AS count FROM keywords k Left Join wallpaper_keywords wk ON wk.keyword_id = k.id GROUP BY wk.keyword_id, k.keyword ORDER BY count DESC limit 100;

 
+----------+-------+ 
| keyword | count | 
+----------+-------+ 
| computer | 10 | 
| road  |  4 | 
| tree  |  4 | 
| window |  4 | 
| nature |  4 | 
| forest |  3 | 
| cars  |  3 | 
| mazda |  3 | 
| abstract |  3 | 
| funny |  3 | 
| sport |  3 | 
| sea  |  3 | 
| city  |  3 | 
| warrior |  2 | 
| bird  |  2 | 
| lights |  1 | 
| summer |  1 | 
| space |  1 | 
| dusk  |  1 | 
| ubuntu |  1 | 
+----------+-------+ 

explain: 

+----+-------------+--------------------+-------+---------------+---------+---------+------+------+----------------------------------------------+ 
| id | select_type | table    | type | possible_keys | key  | key_len | ref | rows | Extra          | 
+----+-------------+--------------------+-------+---------------+---------+---------+------+------+----------------------------------------------+ 
| 1 | PRIMARY  | keywords   | index | NULL   | keyword | 99  | NULL | 20 | Using index; Using temporary; Using filesort | 
| 1 | PRIMARY  |   | ALL | NULL   | NULL | NULL | NULL | 54 |            | 
| 2 | DERIVED  | wallpaper_keywords | index | NULL   | PRIMARY | 3  | NULL | 54 |            | 
+----+-------------+--------------------+-------+---------------+---------+---------+------+------+----------------------------------------------+ 
3 rows in set (0.00 sec) 

编辑 另一个查询： SELECT count,k.keyword from (SELECT * , count(wk.keyword_id) AS count FROM wallpaper_keywords wk GROUP BY wk.keyword_id LIMIT 50000) as data left join keywords as k on k.id = data.keyword_id order by count desc limit 500

+----+-------------+------------+--------+---------------+------------+---------+-----------------+------+----------------+ 
| id | select_type | table  | type | possible_keys | key  | key_len | ref    | rows | Extra   | 
+----+-------------+------------+--------+---------------+------------+---------+-----------------+------+----------------+ 
| 1 | PRIMARY  | | ALL | NULL   | NULL  | NULL | NULL   | 20 | Using filesort | 
| 1 | PRIMARY  | k   | eq_ref | PRIMARY  | PRIMARY | 3  | data.keyword_id | 1 |    | 
| 2 | DERIVED  | wk   | index | NULL   | keyword_id | 3  | NULL   | 59 |    | 
+----+-------------+------------+--------+---------------+------------+---------+-----------------+------+----------------+ 

的问题将是现在 - 有没有更好的解决办法？更便宜（SHOW STATUS LIKE'last_query_cost';）方法来计算它？

Answer 1

要计算每个关键字的总价值，请在表格关键字中使用附加字段（total_count），并通过每次添加新关键字将+1添加到此字段中 - 将来您的数据库会非常简单，您将拥有100 000个记录。