Question

我有一个超过200万行的表，我需要在循环中快速选择查询。

SELECT ID,WebSite FROM `CompanyData` WHERE A1='data1' OR A2='data2' OR A3='data3'

它需要300毫秒。我觉得不应该花这么多时间。以下是该查询的EXPLAIN：

--------+---------------------------------------------------------------------------------------------------------------------------+
| id | select_type | table    | type  | possible_keys  | key      |  key_len    | ref  | rows  | Extra                              |
+----+-------------+----------+-------+---------------+------+---------+------+---------+-------------------------------------------+
|  1 | SIMPLE     | CompanyData | index | A1,A2,A3     | A1,A2,A3 | 153,153,153 | NULL | 3     | Using union(A1,A2,A3); Using where |
+----+-------------+----------+-------+---------------+------+---------+------+---------+-------------------------------------------+

这是表结构：

CREATE TABLE `CompanyData` (
  `ID` int(11) NOT NULL AUTO_INCREMENT,
  `WebSite` varchar(150) DEFAULT NULL,
  `CompanyName` varchar(200) DEFAULT NULL,
  `A1` varchar(150) DEFAULT NULL,
  `A2` varchar(150) DEFAULT NULL,
  `A3` varchar(150) DEFAULT NULL,
  PRIMARY KEY (`ID`),
  UNIQUE KEY `WebSite` (`WebSite`,`CompanyName`),
  KEY `CompanyName` (`CompanyName`),
  KEY `A1` (`A1`),
  KEY `A2` (`A2`),
  KEY `A3` (`A3`)
) ENGINE=InnoDB AUTO_INCREMENT=3931223 DEFAULT CHARSET=latin1

最近我已经在表格中插入了另外1000万条记录。然后一样查询大约需要3秒钟。

请建议一种改进Select查询查询的方法。即使我准备重组桌子。

由于

Answer 1

MySQL很难用OR来优化条件。你可能会更好地尝试：

SELECT ID, WebSite
FROM `CompanyData`
WHERE A1 = 'data1'
UNION
SELECT ID, WebSite
FROM `CompanyData`
WHERE A2 = 'data2' 
UNION
SELECT ID, WebSite
FROM `CompanyData`
WHERE A3 = 'data3';

请注意，这会使用UNION而不是UNION ALL。 UNION ALL的替代版本看起来像这样（假设值永远不是NULL）：

SELECT ID, WebSite
FROM `CompanyData`
WHERE A1 = 'data1'
UNION ALL
SELECT ID, WebSite
FROM `CompanyData`
WHERE A2 = 'data2' AND A1 <> 'data1'
UNION ALL
SELECT ID, WebSite
FROM `CompanyData`
WHERE A3 = 'data3' AND A1 <> 'data1' AND A2 <> 'data2';

对于此查询，最佳索引是复合索引：(A1, ID, WebSite)，(A2, A1, ID, Website)和(A3, A1, A2, ID, WebSite)。

Answer 2

跨列显示的数组是有问题的。

试一试......

CREATE TABLE `CompanyData` (
    `ID` int(11) NOT NULL AUTO_INCREMENT, 
    `WebSite` varchar(150) DEFAULT NULL, 
    `CompanyName` varchar(200) DEFAULT NULL, 
    PRIMARY KEY (`ID`), 
    UNIQUE KEY `WebSite` (`WebSite`,`CompanyName`), 
    KEY `CompanyName` (`CompanyName`), 
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
CREATE TABLE `Stuff` (
    `CompanyID` int(11) NOT NULL
    `A` varchar(150) NOT NULL, 
    PRIMARY KEY (A, CompanyID)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

SELECT  c.ID, c.WebSite
    FROM  CompanyData AS c
    JOIN  Stuff AS s ON c.ID = s.CompanyID
    WHERE  s.A IN ('data1', 'data2', 'data3');

MYSQL - 具有多个OR条件的选择查询是慢的

2 个答案: