我继承了以下查询和数据库结构，我想优化它，因为它很慢。它包含连接和子查询，我读过这不是一个好的计划。我已经尝试了各种方法来改进它，但我遇到了困难。
如果它很好，那么它很好，但如果有改进的建议，我将非常感激......
该查询从各种表中提取数据，以生成关于供应商网站点击次数的报告，供应商的电话号码“显示”以及供应商发送的电子邮件。
WHERE子句使用1 = 1，因为有时会添加条件以按地区，县和供应商的业务类型过滤报表。
从mysql_slow日志复制代码以插入所有$变量。表的结构是从mysql转储输出的。
SELECT Business.*,
( SELECT Count(Message.id) FROM messages as Message
WHERE (U.id = Message.from_to OR U.id = Message.user_id)
AND Message.created BETWEEN '2014-04-01 00:00:00' and '2014-04-30 23:59:59'
) as message_no,
( SELECT Count(DISTINCT(MessageUnique.user_id)) FROM messages as MessageUnique
WHERE (U.id = MessageUnique.from_to OR U.id = MessageUnique.user_id)
AND (MessageUnique.parent_message_id is null OR MessageUnique.parent_message_id = MessageUnique.id)
AND MessageUnique.created BETWEEN '2014-04-01 00:00:00' and '2014-04-30 23:59:59'
) as message_unique_no,
( SELECT Count(*) FROM business_counties as bc2
WHERE Business.id = bc2.business_id ) as county_no,
( SELECT Count(click.id) FROM business_clickthroughs as click
WHERE Business.id = click.business_id
AND click.created BETWEEN '2014-04-01 00:00:00' and '2014-04-30 23:59:59'
) as clicks,
( SELECT Count(*) FROM business_regions as br2
WHERE Business.id = br2.business_id ) as region_no,
( SELECT count(BusinessReveal.id) as reveal_no FROM business_reveals as BusinessReveal
WHERE 1=1
AND BusinessReveal.created BETWEEN '2014-04-01 00:00:00' and '2014-04-30 23:59:59'
AND BusinessReveal.business_id = Business.id
) as reveals_no
FROM businesses as Business
LEFT JOIN users as U ON Business.id = U.business_id
LEFT JOIN business_counties as bc ON Business.id = bc.business_id
LEFT JOIN businesses_business_types as bt ON Business.id = bt.business_id
LEFT JOIN business_regions as br ON Business.id = br.business_id
WHERE 1=1
Group By Business.id;
/*
Navicat MySQL Data Transfer
Source Server : _Localhost
Source Server Type : MySQL
Source Server Version : 50530
Target Server Type : MySQL
Target Server Version : 50530
File Encoding : utf-8
*/
-- ----------------------------
-- Table structure for `business_clickthroughs`
-- ----------------------------
DROP TABLE IF EXISTS `business_clickthroughs`;
CREATE TABLE `business_clickthroughs` (
`id` bigint(12) unsigned NOT NULL AUTO_INCREMENT,
`business_id` int(8) unsigned NOT NULL,
`registered_user` tinyint(1) unsigned DEFAULT '0',
`created` datetime NOT NULL,
PRIMARY KEY (`id`),
KEY `bid` (`business_id`)
) ENGINE=InnoDB AUTO_INCREMENT=29357 DEFAULT CHARSET=utf8 ROW_FORMAT=COMPACT;
-- ----------------------------
-- Table structure for `business_counties`
-- ----------------------------
DROP TABLE IF EXISTS `business_counties`;
CREATE TABLE `business_counties` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`business_id` int(11) NOT NULL,
`county_id` int(11) NOT NULL,
PRIMARY KEY (`id`),
KEY `bcid` (`business_id`)
) ENGINE=MyISAM AUTO_INCREMENT=20124 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci ROW_FORMAT=FIXED;
-- ----------------------------
-- Table structure for `business_regions`
-- ----------------------------
DROP TABLE IF EXISTS `business_regions`;
CREATE TABLE `business_regions` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`business_id` int(11) NOT NULL,
`region_id` int(11) NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=MyISAM AUTO_INCREMENT=2719 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci ROW_FORMAT=FIXED;
-- ----------------------------
-- Table structure for `business_reveals`
-- ----------------------------
DROP TABLE IF EXISTS `business_reveals`;
CREATE TABLE `business_reveals` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`business_id` int(11) NOT NULL,
`customer_id` int(11) DEFAULT NULL,
`created` datetime NOT NULL,
`modified` datetime NOT NULL,
PRIMARY KEY (`id`),
KEY `bid` (`business_id`)
) ENGINE=InnoDB AUTO_INCREMENT=3172 DEFAULT CHARSET=latin1 ROW_FORMAT=COMPACT;
-- ----------------------------
-- Table structure for `businesses_business_types`
-- ----------------------------
DROP TABLE IF EXISTS `businesses_business_types`;
CREATE TABLE `businesses_business_types` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`business_id` int(11) NOT NULL,
`business_type_id` int(11) NOT NULL,
`level` int(2) NOT NULL DEFAULT '2',
PRIMARY KEY (`id`),
KEY `bid` (`business_id`) COMMENT '(null)'
) ENGINE=MyISAM AUTO_INCREMENT=4484 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci ROW_FORMAT=FIXED;
-- ----------------------------
-- Table structure for `messages`
-- ----------------------------
DROP TABLE IF EXISTS `messages`;
CREATE TABLE `messages` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`subject` varchar(500) DEFAULT NULL,
`message` text,
`user_id` int(11) DEFAULT NULL,
`message_folder_id` int(11) DEFAULT NULL,
`parent_message_id` int(11) DEFAULT NULL,
`status` int(11) DEFAULT NULL,
`direction` int(11) DEFAULT NULL,
`from_to` varchar(500) DEFAULT NULL,
`attachment` varchar(500) DEFAULT NULL,
`created` datetime DEFAULT NULL,
`modified` datetime DEFAULT NULL,
`guest_sender` varchar(255) DEFAULT NULL,
PRIMARY KEY (`id`),
KEY `fromto` (`from_to`(255)),
KEY `uid` (`user_id`),
KEY `pmid` (`parent_message_id`)
) ENGINE=InnoDB AUTO_INCREMENT=4582 DEFAULT CHARSET=utf8 ROW_FORMAT=COMPACT;
-- ----------------------------
-- Table structure for `users`
-- ----------------------------
DROP TABLE IF EXISTS `users`;
CREATE TABLE `users` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`login` varchar(255) COLLATE latin1_general_ci NOT NULL,
`password` varchar(255) COLLATE latin1_general_ci NOT NULL,
`name` varchar(255) COLLATE latin1_general_ci NOT NULL,
`email` varchar(255) COLLATE latin1_general_ci NOT NULL,
`title` varchar(20) COLLATE latin1_general_ci NOT NULL,
`firstname` varchar(255) COLLATE latin1_general_ci NOT NULL,
`lastname` varchar(255) COLLATE latin1_general_ci NOT NULL,
`active` tinyint(1) NOT NULL DEFAULT '0',
`first_visit` tinyint(1) NOT NULL DEFAULT '1',
`signature` text COLLATE latin1_general_ci,
`type` varchar(45) COLLATE latin1_general_ci DEFAULT 'customer',
`business_id` int(11) DEFAULT NULL,
`admin_monitor` tinyint(1) NOT NULL DEFAULT '0',
`partner_name` varchar(255) COLLATE latin1_general_ci DEFAULT NULL,
`postcode` varchar(255) COLLATE latin1_general_ci DEFAULT NULL,
`venue_postcode` varchar(255) COLLATE latin1_general_ci DEFAULT NULL,
`wedding_date` datetime DEFAULT NULL,
`phone` varchar(255) COLLATE latin1_general_ci NOT NULL,
`register_date` datetime DEFAULT NULL,
`event` text COLLATE latin1_general_ci,
`mailing_list` tinyint(1) NOT NULL DEFAULT '0',
`created` datetime NOT NULL,
`modified` datetime NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=MyISAM AUTO_INCREMENT=2854 DEFAULT CHARSET=latin1 COLLATE=latin1_general_ci ROW_FORMAT=DYNAMIC;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY Business ALL - - - - 444 Using temporary; Using filesort
1 PRIMARY U ALL - - - - 2658 -
1 PRIMARY bc ref bcid bcid 4 Business.id 7 Using index
1 PRIMARY bt ref bid bid 4 Business.id 9 Using index
1 PRIMARY br ALL - - - - 440 -
7 DEPENDENT SUBQUERY BusinessReveal ref bid bid 4 func 5 Using where
6 DEPENDENT SUBQUERY br2 ALL - - - - 440 Using where
5 DEPENDENT SUBQUERY click ref bid bid 4 func 22 Using where
4 DEPENDENT SUBQUERY bc2 ref bcid bcid 4 func 7 Using index
3 DEPENDENT SUBQUERY MessageUnique ALL fromto,uid,pmid - - - 4958 Using where
2 DEPENDENT SUBQUERY Message ALL fromto,uid - - - 4958 Using where
答案 0 :(得分：0)
您的查询有6个相关的子查询，总共返回444行。对于每个返回的行，有效地执行这些相关子查询中的每一个。因此，您的单个查询导致不到3000个查询。
我个人更喜欢避免使用大型连接或加入子查询。但是它取决于返回的行数
此外，您还可以直接加入正在进行左连接的表格，这将生成很多重复项，然后GROUP BY将其排除。由于您没有直接从大多数表中取任何内容而且GROUP BY处于看似独特的键上，因此它似乎无关紧要。
如果您保留相关的子查询： -
SELECT Count(Message.id) FROM messages as Message
WHERE (U.id = Message.from_to OR U.id = Message.user_id)
AND Message.created BETWEEN '2014-04-01 00:00:00' and '2014-04-30 23:59:59'
此子查询在此表上没有有用的索引。在为U.id检查2个不同的列时，可以在那里完成的工作并不多，但创建的索引会有所帮助。一旦检查from_to并检查user_id并将结果一起添加，复制此子查询可能会更好。然后你可以在相关的id字段和日期上有一个索引。
此外，您正在计算看似唯一键的值，因此永远不应该为空。
SELECT Count(DISTINCT(MessageUnique.user_id)) FROM messages as MessageUnique
WHERE (U.id = MessageUnique.from_to OR U.id = MessageUnique.user_id)
AND (MessageUnique.parent_message_id is null OR MessageUnique.parent_message_id = MessageUnique.id)
AND MessageUnique.created BETWEEN '2014-04-01 00:00:00' and '2014-04-30 23:59:59'
与上一个子查询相同的问题。
SELECT Count(*) FROM business_counties as bc2
WHERE Business.id = bc2.business_id
这在business_id上有一个关键，应该没问题
SELECT Count(click.id) FROM business_clickthroughs as click
WHERE Business.id = click.business_id
AND click.created BETWEEN '2014-04-01 00:00:00' and '2014-04-30 23:59:59'
虽然在业务ID上编入索引，但没有包含业务ID和创建日期的索引，这可能对此有所帮助。
SELECT Count(*) FROM business_regions as br2
WHERE Business.id = br2.business_id
这需要在业务范围表
上的business_id索引SELECT count(BusinessReveal.id) as reveal_no FROM business_reveals as BusinessReveal
WHERE 1=1
AND BusinessReveal.created BETWEEN '2014-04-01 00:00:00' and '2014-04-30 23:59:59'
AND BusinessReveal.business_id = Business.id
这里的密钥不包括创建日期，只包括业务ID。
如果你想尝试对子查询进行连接（虽然MySQL在加入子查询方面很差）可能会更有效率，但这样的事情（未经测试）： -
SELECT Business.*,
mess_1.mess_count + mess_2.mess_count as message_no,
mess_3.mess_count + mess_4.mess_count as message_unique_no,
business1.county_no,
click1.clicks,
business_regions.region_no,
business_reveals1.reveals_no
FROM businesses as Business
LEFT JOIN users as U ON Business.id = U.business_id
LEFT OUTER JOIN
(
SELECT Message.from_to, Count(Message.id) AS mess_count
FROM messages as Message
WHERE Message.created BETWEEN '2014-04-01 00:00:00' and '2014-04-30 23:59:59'
GROUP BY Message.from_to
) AS mess_1
ON U.id = mess_1.from_to
LEFT OUTER JOIN
(
SELECT Message.user_id, Count(Message.id) AS mess_count
FROM messages as Message
WHERE Message.created BETWEEN '2014-04-01 00:00:00' and '2014-04-30 23:59:59'
GROUP BY Message.user_id
) AS mess_2
ON U.id = mess_2.user_id
LEFT OUTER JOIN
(
SELECT MessageUnique.from_to, Count(DISTINCT(MessageUnique.user_id)) AS mess_count
FROM messages as MessageUnique
WHERE (MessageUnique.parent_message_id is null OR MessageUnique.parent_message_id = MessageUnique.id)
AND MessageUnique.created BETWEEN '2014-04-01 00:00:00' and '2014-04-30 23:59:59'
GROUP BY MessageUnique.from_to
) AS mess_3
ON U.id = mess_3.from_to
LEFT OUTER JOIN
(
SELECT MessageUnique.user_id, Count(DISTINCT(MessageUnique.user_id)) AS mess_count
FROM messages as MessageUnique
WHERE (MessageUnique.parent_message_id is null OR MessageUnique.parent_message_id = MessageUnique.id)
AND MessageUnique.created BETWEEN '2014-04-01 00:00:00' and '2014-04-30 23:59:59'
GROUP BY MessageUnique.user_id
) AS mess_4
ON U.id = mess_4.from_to
LEFT OUTER JOIN
(
SELECT business_id, Count(*) AS county_no
FROM business_counties as bc2
GROUP BY Business.id
) as business1
ON Business.id = business1.business_id
LEFT OUTER JOIN
(
SELECT click.business_id, Count(click.id) AS clicks
FROM business_clickthroughs as click
WHERE click.created BETWEEN '2014-04-01 00:00:00' and '2014-04-30 23:59:59'
GROUP BY click.business_id
) as click1
ON Business.id = click1.business_id
LEFT OUTER JOIN
(
SELECT br2.business_id, Count(*) AS region_no
FROM business_regions as br2
WHERE Business.id = br2.business_id
GROUP BY br2.business_id
) as business_regions
ON Business.id = business_regions.business_id
LEFT OUTER JOIN
(
SELECT BusinessReveal.business_id, count(BusinessReveal.id) as reveal_no
FROM business_reveals as BusinessReveal
WHERE BusinessReveal.created BETWEEN '2014-04-01 00:00:00' and '2014-04-30 23:59:59'
GROUP BY BusinessReveal.business_id
) as business_reveals1
ON business_reveals1.business_id = Business.id