Question

我有两张桌子：

第一

    CREATE TABLE IF NOT EXISTS `tags` (
  `i` int(10) NOT NULL AUTO_INCREMENT,
  `id` int(10) NOT NULL,
  `k` varchar(32) COLLATE utf8_bin NOT NULL,
  PRIMARY KEY (`i`),
  KEY `k` (`k`)
) ENGINE=MyISAM  DEFAULT CHARSET=utf8 COLLATE=utf8_bin AUTO_INCREMENT=1505426 ;

和第二名：

CREATE TABLE IF NOT EXISTS `w` (
  `id` int(7) NOT NULL,
  `title` varchar(255) COLLATE utf8_bin NOT NULL,
  `k1` varchar(24) COLLATE utf8_bin NOT NULL,
  `k2` varchar(24) COLLATE utf8_bin NOT NULL,
  `k3` varchar(24) COLLATE utf8_bin NOT NULL,
  `k4` varchar(24) COLLATE utf8_bin NOT NULL,
  `k5` varchar(24) COLLATE utf8_bin NOT NULL,
  `k6` varchar(24) COLLATE utf8_bin NOT NULL,
  `k7` varchar(24) COLLATE utf8_bin NOT NULL,
  `k8` varchar(24) COLLATE utf8_bin NOT NULL,
  `w` int(5) NOT NULL,
  `h` int(5) NOT NULL,
  `s` varchar(32) COLLATE utf8_bin NOT NULL,
  `r` varchar(11) COLLATE utf8_bin NOT NULL,
  `v` int(7) NOT NULL,
  `c` varchar(32) COLLATE utf8_bin NOT NULL,
  `c1` varchar(6) COLLATE utf8_bin NOT NULL,
  `c2` varchar(6) COLLATE utf8_bin NOT NULL,
  `c3` varchar(6) COLLATE utf8_bin NOT NULL,
  `c4` varchar(6) COLLATE utf8_bin NOT NULL,
  `c5` varchar(6) COLLATE utf8_bin NOT NULL,
  `c6` varchar(6) COLLATE utf8_bin NOT NULL,
  `m` varchar(4) COLLATE utf8_bin NOT NULL,
  `t` int(10) NOT NULL,
  `i` int(6) NOT NULL,
  `o` int(6) NOT NULL,
  `f` varchar(255) COLLATE utf8_bin NOT NULL,
  PRIMARY KEY (`id`),
  KEY `keywords` (`k1`,`k2`,`k3`,`k4`,`k5`,`k6`,`k7`,`k8`),
  KEY `category` (`c`),
  KEY `color1` (`c1`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_bin ROW_FORMAT=DYNAMIC;

我正在尝试从表'tags'中搜索2个单词（$ search1 + $ search2）并在'w'表中找到id。查询：

SELECT w.id,w.title,w.k1,w.k2,w.k3,w.k4,w.k5,w.k6,w.k7,w.w,w.h,w.s,w.c1,w.c2,w.c3,w.c4,w.c5,w.c6,w.m,w.f
FROM tags,tags as tags2,w
WHERE tags.k ='$search1' AND tags2.k = '$search2'
and tags.id = tags2.id and tags2.id = w.id
ORDER BY `w`.`id`desc limit 24

问题是EXPLAIN函数显示“使用where;使用临时;使用filesort” 另外我相信还有另一种方法来优化我的类型搜索系统。实际上所有数据都在'w'表中，我只是不知道如何正确搜索它。我将不胜感激任何帮助。

修改：有关此内容的更多信息

表'标签'1505425记录InnoDB = 65,9 MiB

表'w'398900 rercords，InnoDB = 140,3 MiB

此后（更新）查询：

select `w`.`id` AS `id`,`w`.`title` AS `title`,`w`.`k1` AS `k1`,`w`.`k2` AS `k2`,`w`.`k3` AS `k3`,`w`.`k4` AS `k4`,`w`.`k5` AS `k5`,`w`.`k6` AS `k6`,`w`.`k7` AS `k7`,`w`.`k8` AS `k8`,`w`.`w` AS `w`,`w`.`h` AS `h`,`w`.`s` AS `s`,`w`.`c1` AS `c1`,`w`.`c2` AS `c2`,`w`.`c3` AS `c3`,`w`.`c4` AS `c4`,`w`.`c5` AS `c5`,`w`.`c6` AS `c6`,`w`.`m` AS `m`,`w`.`f` AS `f` from `tags` join `tags` `tags2` join `w` where ((`tags`.`k` = '$search1') and (`tags2`.`id` = `tags`.`id`) and (`w`.`id` = `tags`.`id`) and (`tags2`.`k` = '$search2')) order by `tags`.`i` desc limit 0,24;

mysql仍显示：

+----+-------------+------------+--------+---------------+---------+---------+-------------+------+----------+-----------------------------+
| id | select_type | table      | type   | possible_keys | key     | key_len | ref         | rows | filtered | Extra                       |
+----+-------------+------------+--------+---------------+---------+---------+-------------+------+----------+-----------------------------+
|  1 | SIMPLE      | tags       | ref    | k,id          | k       | 98      | const       |  902 |   100.00 | Using where; Using filesort |
|  1 | SIMPLE      | tags2      | ref    | k,id          | id      | 4       | db.tags.id  |    4 |   100.00 | Using where                 |
|  1 | SIMPLE      | w          | eq_ref | PRIMARY       | PRIMARY | 4       | db.tags2.id |    1 |   100.00 | Using where                 |
+----+-------------+------------+--------+---------------+---------+---------+-------------+------+----------+-----------------------------+
3 rows in set, 1 warning (0.00 sec)

一个警告，仍然一切都保持不变，是否有任何解决方案可以获得更好的性能？目前它工作正常，但后来我认为一切都会越来越慢。

Answer 1

你正在混合存储引擎; mySQL很难跨存储引擎连接表。

在：

mysql> explain SELECT w.id,w.title,w.k1,w.k2,w.k3,w.k4,w.k5,w.k6,w.k7,w.w,w.h,w.s,w.c1,w.c2,w.c3,w.c4,w.c5,w.c6,w.m,w.f FROM tags,tags as tags2,w WHERE tags.k ='$search1' AND tags2.k = 'search2' and tags.id = tags2.id and tags2.id = w.id ORDER BY `w`.`id`desc limit 24;
+----+-------------+-------+--------+---------------+---------+---------+-------------+------+----------------------------------------------+
| id | select_type | table | type   | possible_keys | key     | key_len | ref         | rows | Extra                                        |
+----+-------------+-------+--------+---------------+---------+---------+-------------+------+----------------------------------------------+
|  1 | SIMPLE      | tags  | ref    | k             | k       | 98      | const       |    1 | Using where; Using temporary; Using filesort |
|  1 | SIMPLE      | tags2 | ref    | k             | k       | 98      | const       |    1 | Using where                                  |
|  1 | SIMPLE      | w     | eq_ref | PRIMARY       | PRIMARY | 4       | tmp.tags.id |    1 |                                              |
+----+-------------+-------+--------+---------------+---------+---------+-------------+------+----------------------------------------------+

将w更改为MyISAM：

mysql> alter table w engine MyISAM;
Query OK, 1 row affected (0.01 sec)
Records: 1  Duplicates: 0  Warnings: 0

后：

mysql> explain SELECT w.id,w.title,w.k1,w.k2,w.k3,w.k4,w.k5,w.k6,w.k7,w.w,w.h,w.s,w.c1,w.c2,w.c3,w.c4,w.c5,w.c6,w.m,w.f FROM tags,tags as tags2,w WHERE tags.k ='$search1' AND tags2.k = 'search2' and tags.id = tags2.id and tags2.id = w.id ORDER BY `w`.`id`desc limit 24;
+----+-------------+-------+--------+---------------+------+---------+-------+------+-------------+
| id | select_type | table | type   | possible_keys | key  | key_len | ref   | rows | Extra       |
+----+-------------+-------+--------+---------------+------+---------+-------+------+-------------+
|  1 | SIMPLE      | w     | system | PRIMARY       | NULL | NULL    | NULL  |    1 |             |
|  1 | SIMPLE      | tags  | ref    | k             | k    | 98      | const |    1 | Using where |
|  1 | SIMPLE      | tags2 | ref    | k             | k    | 98      | const |    1 | Using where |
+----+-------------+-------+--------+---------------+------+---------+-------+------+-------------+
3 rows in set (0.00 sec)

Answer 2

Vagiz，您的更新查询似乎没问题：

select `w`.`id` AS `id`,`w`.`title` AS `title`,`w`.`k1` AS `k1`,`w`.`k2` AS `k2`,
`w`.`k3` AS `k3`,`w`.`k4` AS `k4`,`w`.`k5` AS `k5`,`w`.`k6` AS `k6`,`w`.
`k7` AS `k7`,`w`.`k8` AS `k8`,`w`.`w` AS `w`,`w`.`h` AS `h`,`w`.`s` AS `s`,
`w`.`c1` AS `c1`,`w`.`c2` AS `c2`,`w`.`c3` AS `c3`,`w`.`c4` AS `c4`,
`w`.`c5` AS `c5`,`w`.`c6` AS `c6`,`w`.`m` AS `m`,`w`.`f` AS `f`
from `tags` join `tags` `tags2` join `w` where ((`tags`.`k` = '$search1') 
and (`tags2`.`id` = `tags`.`id`) and (`w`.`id` = `tags`.`id`) 
and (`tags2`.`k` = '$search2')) order by `tags`.`i` desc limit 0,24;

如果它产生以下解释结果：

+----+-------------+------------+--------+---------------+---------+---------+-------------+------+----------+-----------------------------+
| id | select_type | table      | type   | possible_keys | key     | key_len | ref         | rows | filtered | Extra                       |
+----+-------------+------------+--------+---------------+---------+---------+-------------+------+----------+-----------------------------+
|  1 | SIMPLE      | tags       | ref    | k,id          | k       | 98      | const       |  902 |   100.00 | Using where; Using filesort |
|  1 | SIMPLE      | tags2      | ref    | k,id          | id      | 4       | db.tags.id  |    4 |   100.00 | Using where                 |
|  1 | SIMPLE      | w          | eq_ref | PRIMARY       | PRIMARY | 4       | db.tags2.id |    1 |   100.00 | Using where                 |
+----+-------------+------------+--------+---------------+---------+---------+-------------+------+----------+-----------------------------+
3 rows in set, 1 warning (0.00 sec)

不要担心文件排序和性能。来自Mysql Performance Blog：

事实是，filesort的名字很糟糕。任何时候都不能排序从索引执行，它是一个文件排序。它与此无关文件。应该将Filesort称为“排序”。它很快就会出类拔萃。

如何优化两个表的搜索？

2 个答案: