如何提高查询执行的性能

时间:2014-09-27 05:44:57

标签: join optimization indexing query-optimization

以下查询需要花费时间(2.3秒)才能执行。

SELECT *, COUNT(c2.id) AS c2__0 
FROM countryMaster c, stateMaster s, cityMaster c2, categoryMaster c3, categoryMaster c4, product p 
INNER JOIN user u ON ((u.id = p.user_id AND u.is_active = 1))
WHERE (p.category_id = c4.id 
AND c2.id = p.x_area_id
AND c2.parent_id = s.id 
AND s.parent_id = c.id AND c3.id IN ('1271')
AND c4.rgt = (c4.lft + 1)
AND c4.lft BETWEEN c3.lft AND c3.rgt AND p.status = 1)
GROUP BY c.id;


Explain:    
*************************** 1. row ***************************
           id: 1
  select_type: SIMPLE
        table: c3
         type: const
possible_keys: PRIMARY,lft_rgt_inx
          key: PRIMARY
      key_len: 4
          ref: const
         rows: 1
        Extra: Using temporary; Using filesort
*************************** 2. row ***************************
           id: 1
  select_type: SIMPLE
        table: p
         type: ALL
possible_keys: INX_cmp_sx,status
          key: NULL
      key_len: NULL
          ref: NULL
         rows: 29958
        Extra: Using where
*************************** 3. row ***************************
           id: 1
  select_type: SIMPLE
        table: c4
         type: eq_ref
possible_keys: PRIMARY,lft_rgt_inx
          key: PRIMARY
      key_len: 4
          ref: yozoa1_live.p.category_id
         rows: 1
        Extra: Using where
*************************** 4. row ***************************
           id: 1
  select_type: SIMPLE
        table: u
         type: eq_ref
possible_keys: PRIMARY,is_active
          key: PRIMARY
      key_len: 4
          ref: yozoa1_live.p.user_id
         rows: 1
        Extra: Using where
*************************** 5. row ***************************
           id: 1
  select_type: SIMPLE
        table: c2
         type: eq_ref
possible_keys: PRIMARY,parent_id
          key: PRIMARY
      key_len: 4
          ref: yozoa1_live.p.x_area_id
         rows: 1
        Extra: 
*************************** 6. row ***************************
           id: 1
  select_type: SIMPLE
        table: s
         type: eq_ref
possible_keys: PRIMARY,parent_id
          key: PRIMARY
      key_len: 4
          ref: yozoa1_live.c2.parent_id
         rows: 1
        Extra: 
*************************** 7. row ***************************
           id: 1
  select_type: SIMPLE
        table: c
         type: eq_ref
possible_keys: PRIMARY
          key: PRIMARY
      key_len: 4
          ref: yozoa1_live.s.parent_id
         rows: 1
        Extra: 


Show create table -     
CREATE TABLE `categoryMaster` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(255) NOT NULL,
  `description` text NOT NULL,
  `logo` varchar(255) NOT NULL,
  `is_visible` tinyint(1) NOT NULL DEFAULT '1',
  `is_featured` tinyint(1) NOT NULL DEFAULT '0',
  `is_map` tinyint(1) NOT NULL DEFAULT '0',
  `is_price_required` tinyint(1) NOT NULL DEFAULT '1',
  `parent_id` int(11) NOT NULL DEFAULT '0',
  `lft` int(11) NOT NULL DEFAULT '0',
  `rgt` int(11) NOT NULL DEFAULT '0',
  `level` tinyint(4) NOT NULL DEFAULT '0',
  `sort_order` smallint(6) NOT NULL DEFAULT '0',
  `product_count` int(11) NOT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `lft_rgt_inx` (`lft`,`rgt`),
  KEY `parent_id` (`parent_id`),
  KEY `product_count` (`product_count`)
) ENGINE=MyISAM


CREATE TABLE `productMaster` (
  `id` bigint(20) NOT NULL AUTO_INCREMENT,
  `name` varchar(255) NOT NULL,
  `description` longtext NOT NULL,
  `sub_name` varchar(255) NOT NULL,
  `sub_description` longtext NOT NULL,
  `image` varchar(255) NOT NULL,
  `category_id` int(11) NOT NULL,
  `is_new` tinyint(1) NOT NULL DEFAULT '1',
  `status` tinyint(1) NOT NULL DEFAULT '-1',
  `user_id` int(11) NOT NULL,
  `currency_main` varchar(4) NOT NULL DEFAULT 'MNT',
  `price_original` double NOT NULL DEFAULT '0',
  `price_global` double NOT NULL DEFAULT '0',
  `attribute_value_ids` text,
  `created_at` datetime DEFAULT NULL,
  `updated_at` datetime DEFAULT NULL,
  `confirmed_at` datetime DEFAULT NULL,
  `duration` int(4) NOT NULL DEFAULT '7',
  `rental_duration` varchar(50) DEFAULT NULL,
  `buy_online` tinyint(1) NOT NULL DEFAULT '0',
  `internal` tinyint(1) NOT NULL DEFAULT '0',
  `delivery_status` smallint(1) NOT NULL DEFAULT '1'
  `delivery_type` smallint(1) NOT NULL DEFAULT '1'
  `phone_cell` varchar(50) DEFAULT NULL,
  `phone_home` varchar(50) DEFAULT NULL,
  `surname` varchar(100) DEFAULT NULL,
  `x_area_id` int(11) NOT NULL,
  `x_area_location_id` int(11) DEFAULT NULL,
  `sublocality_id` int(11) DEFAULT NULL,
  `product_posting_price` double NOT NULL,
  `is_paid` tinyint(1) NOT NULL,
  `product_posting_currency` varchar(3) NOT NULL,
  `map_lat` double NOT NULL,
  `map_lng` double NOT NULL,
  `product_company_contact_info_id` int(11) NOT NULL,
  `backup_status` tinyint(1) NOT NULL DEFAULT '4',
  `is_scraped` tinyint(1) DEFAULT NULL,
  `sources_id` int(3) NOT NULL,
  `product_source_url` varchar(255) NOT NULL,
  `country_id` int(4) NOT NULL,
  `state_id` int(5) NOT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `UNQ_cmp_icsu` (`id`,`category_id`,`status`,`user_id`),
  KEY `country_id` (`country_id`),
  KEY `state_id` (`state_id`),
  KEY `INX_cmp_sx` (`status`,`x_area_id`),
  KEY `status` (`status`),
  FULLTEXT KEY `name` (`name`),
  FULLTEXT KEY `attribute_value_ids` (`attribute_value_ids`)
) ENGINE=MyISAM


CREATE TABLE `cityMaster` (
  `id` int(10) NOT NULL AUTO_INCREMENT,
  `parent_id` int(6) NOT NULL,
  `name` varchar(255) CHARACTER SET utf8 COLLATE utf8_bin NOT NULL,
  `map_lat` double NOT NULL,
  `map_lng` double NOT NULL,
  `has_sublocality` tinyint(1) NOT NULL DEFAULT '0',
  PRIMARY KEY (`id`),
  KEY `parent_id` (`parent_id`)
) ENGINE=MyISAM


CREATE TABLE `stateMaster` (
  `id` int(6) NOT NULL AUTO_INCREMENT,
  `parent_id` int(3) NOT NULL,
  `name` varchar(255) NOT NULL,
  `map_lat` double NOT NULL,
  `map_lng` double NOT NULL,
  PRIMARY KEY (`id`),
  KEY `parent_id` (`parent_id`)
) ENGINE=MyISAM


CREATE TABLE `countryMaster` (
  `id` int(3) NOT NULL AUTO_INCREMENT,
  `name` varchar(255) NOT NULL,
  `country_code` varchar(2) CHARACTER SET latin1 NOT NULL,
  `map_lat` double NOT NULL,
  `map_lng` double NOT NULL,
  `is_active` tinyint(1) NOT NULL DEFAULT '1',
  PRIMARY KEY (`id`)
) ENGINE=MyISAM

请建议我如何通过索引减少此查询的执行时间。 并且还让我知道为什么查询解释在ref列中显示null? 还让我知道优化查询的步骤吗?

1 个答案:

答案 0 :(得分:2)

好的,看看这个,我认为你需要做的是在x_area_id上添加一个索引到productMaster,或者可能是一个多列索引。原因如下:

SELECT *, COUNT(c2.id) AS c2__0 
FROM countryMaster c, stateMaster s, cityMaster c2, categoryMaster c3, categoryMaster c4, product p 
INNER JOIN user u ON ((u.id = p.user_id AND u.is_active = 1))
WHERE (p.category_id = c4.id 
AND c2.id = p.x_area_id
AND c2.parent_id = s.id 
AND s.parent_id = c.id AND c3.id IN ('1271')
AND c4.rgt = (c4.lft + 1)
AND c4.lft BETWEEN c3.lft AND c3.rgt AND p.status = 1)
GROUP BY c.id;

请注意这里的连接条件:

AND c2.id = p.x_area_id

另请注意,在产品主表中,您有

上的索引
 PRIMARY KEY (`id`),
  UNIQUE KEY `UNQ_cmp_icsu` (`id`,`category_id`,`status`,`user_id`),
  KEY `country_id` (`country_id`),
  KEY `state_id` (`state_id`),
  KEY `INX_cmp_sx` (`status`,`x_area_id`),
  KEY `status` (`status`),
  FULLTEXT KEY `name` (`name`),
  FULLTEXT KEY `attribute_value_ids` (`attribute_value_ids`)

值得注意的是,不是x_area_id。

SQL提到可能的密钥的事实与SQL语句的这一部分有关:

AND c4.lft BETWEEN c3.lft AND c3.rgt AND p.status = 1)

实质上,SQL注意到它可能能够使用status = 1来利用INX_cmp_sx键。我已经有一段时间了,因为我在MyISAM上做了很多工作,但我怀疑是因为它选择使用p.user_id上的索引来对用户表进行连接,并且查询优化器决定不执行索引合并。 / p>

如果是我,我会尝试两件事。首先,我只是尝试在x_area_id上添加一个键,看看是否能提高性能(显然可以解释一下......显然)。如果没有,那么我会考虑在(user_id,status和x_area_id)上添加复合索引。确切地说哪个列应该是索引中的第一列,我从这看起来完全清楚...我会猜测状态,但你需要测试它。

另外,我想指出你在productMaster表上的状态索引

  KEY `INX_cmp_sx` (`status`,`x_area_id`),
  KEY `status` (`status`),
由于INX_cmp_sx键,

是多余的。因此,您可能希望尝试使用类似(user_id,status和x_area_id)或(user_id,x_area_id,status)或类似的东西替换状态索引。

从技术上讲,你可以将它们全部单独编入索引,但这有时会适得其反(例如http://www.percona.com/blog/2009/09/19/multi-column-indexes-vs-index-merge/

底线:摆脱状态键并将其替换为(user_id,status和x_area_id)的一些变体。甚至尝试摆脱INX_cmp_sx并将其替换为(status,user_id,x_area_id)或(status,x_area_id,user_id)。你的解释的输出基本上告诉你,MySQL无法找到一种方法来提取对应于(status,user_id,x_area_id)组合的数据的横截面,这些组合可以更简单地读取整个productMaster表。玩这些列上的索引,你应该找到更好的东西。而且,再次,有一个机会,简单地添加x_area_id将直接这一切。我绝对会先尝试一下。