提高SQL查詢性能

Question

我有一個復雜的查詢，需要700毫秒才能在我的計算機上運行。 我發現瓶頸是ORDER BY at_firstname.value子句，但是如何使用索引來改善此問題？

SELECT 
    `e`.*
    , `at_default_billing`.`value` AS `default_billing`
    , `at_billing_postcode`.`value` AS `billing_postcode`
    , `at_billing_city`.`value` AS `billing_city`
    , `at_billing_region`.`value` AS `billing_region`
    , `at_billing_country_id`.`value` AS `billing_country_id`
    , `at_company`.`value` AS `company`
    , `at_firstname`.`value` AS `firstname`
    , `at_lastname`.`value` AS `lastname`
    , CONCAT(at_firstname.value
    , " "
    , at_lastname.value) AS `full_name`
    , `at_phone`.`value` AS `phone`
    , IFNULL(at_phone.value,"N/A") AS `telephone`
    , `e`.`entity_id` AS `id` 
FROM 
    `customer_entity` AS `e`  
LEFT JOIN 
    `customer_entity_int` AS `at_default_billing` 
    ON (`at_default_billing`.`entity_id` = `e`.`entity_id`) 
    AND (`at_default_billing`.`attribute_id` = '13')  
LEFT JOIN 
    `customer_address_entity_varchar` AS `at_billing_postcode` 
    ON (`at_billing_postcode`.`entity_id` = `at_default_billing`.`value`)        
    AND (`at_billing_postcode`.`attribute_id` = '30')  
LEFT JOIN 
    `customer_address_entity_varchar` AS `at_billing_city` 
    ON (`at_billing_city`.`entity_id` = `at_default_billing`.`value`) 
    AND (`at_billing_city`.`attribute_id` = '26')  
LEFT JOIN 
    `customer_address_entity_varchar` AS `at_billing_region` 
    ON (`at_billing_region`.`entity_id` = `at_default_billing`.`value`) 
    AND (`at_billing_region`.`attribute_id` = '28')  
LEFT JOIN 
    `customer_address_entity_varchar` AS `at_billing_country_id` 
    ON (`at_billing_country_id`.`entity_id` = `at_default_billing`.`value`) 
    AND (`at_billing_country_id`.`attribute_id` = '27')  
LEFT JOIN 
    `customer_address_entity_varchar` AS `at_company` 
    ON (`at_company`.`entity_id` = `at_default_billing`.`value`) 
    AND (`at_company`.`attribute_id` = '24')  
LEFT JOIN 
    `customer_entity_varchar` AS `at_firstname` 
    ON (`at_firstname`.`entity_id` = `e`.`entity_id`) 
    AND (`at_firstname`.`attribute_id` = '5')  
LEFT JOIN 
    `customer_entity_varchar` AS `at_lastname` 
    ON (`at_lastname`.`entity_id` = `e`.`entity_id`) 
    AND (`at_lastname`.`attribute_id` = '7')  
LEFT JOIN 
    `customer_entity_varchar` AS `at_phone` 
    ON (`at_phone`.`entity_id` = `e`.`entity_id`) 
    AND (`at_phone`.`attribute_id` = '136')  
ORDER BY 
    `at_firstname`.`value` ASC LIMIT 20

這是執行計划：

查詢說明：

'1','SIMPLE','e',NULL,'ALL',NULL,NULL,NULL,NULL,'19951','100.00','Using temporary; Using filesort'
'1','SIMPLE','at_default_billing',NULL,'eq_ref','UNQ_CUSTOMER_ENTITY_INT_ENTITY_ID_ATTRIBUTE_ID,IDX_CUSTOMER_ENTITY_INT_ATTRIBUTE_ID,IDX_CUSTOMER_ENTITY_INT_ENTITY_ID,IDX_CUSTOMER_ENTITY_INT_ENTITY_ID_ATTRIBUTE_ID_VALUE','UNQ_CUSTOMER_ENTITY_INT_ENTITY_ID_ATTRIBUTE_ID','6','lazurd.e.entity_id,const','1','100.00',NULL
'1','SIMPLE','at_billing_postcode',NULL,'eq_ref','UNQ_CUSTOMER_ADDRESS_ENTITY_VARCHAR_ENTITY_ID_ATTRIBUTE_ID,IDX_CUSTOMER_ADDRESS_ENTITY_VARCHAR_ATTRIBUTE_ID,IDX_CUSTOMER_ADDRESS_ENTITY_VARCHAR_ENTITY_ID,IDX_CUSTOMER_ADDRESS_ENTITY_VARCHAR_ENTITY_ID_ATTRIBUTE_ID_VALUE','UNQ_CUSTOMER_ADDRESS_ENTITY_VARCHAR_ENTITY_ID_ATTRIBUTE_ID','6','lazurd.at_default_billing.value,const','1','100.00','Using where'
'1','SIMPLE','at_billing_city',NULL,'eq_ref','UNQ_CUSTOMER_ADDRESS_ENTITY_VARCHAR_ENTITY_ID_ATTRIBUTE_ID,IDX_CUSTOMER_ADDRESS_ENTITY_VARCHAR_ATTRIBUTE_ID,IDX_CUSTOMER_ADDRESS_ENTITY_VARCHAR_ENTITY_ID,IDX_CUSTOMER_ADDRESS_ENTITY_VARCHAR_ENTITY_ID_ATTRIBUTE_ID_VALUE','UNQ_CUSTOMER_ADDRESS_ENTITY_VARCHAR_ENTITY_ID_ATTRIBUTE_ID','6','lazurd.at_default_billing.value,const','1','100.00','Using where'
'1','SIMPLE','at_billing_region',NULL,'eq_ref','UNQ_CUSTOMER_ADDRESS_ENTITY_VARCHAR_ENTITY_ID_ATTRIBUTE_ID,IDX_CUSTOMER_ADDRESS_ENTITY_VARCHAR_ATTRIBUTE_ID,IDX_CUSTOMER_ADDRESS_ENTITY_VARCHAR_ENTITY_ID,IDX_CUSTOMER_ADDRESS_ENTITY_VARCHAR_ENTITY_ID_ATTRIBUTE_ID_VALUE','UNQ_CUSTOMER_ADDRESS_ENTITY_VARCHAR_ENTITY_ID_ATTRIBUTE_ID','6','lazurd.at_default_billing.value,const','1','100.00','Using where'
'1','SIMPLE','at_billing_country_id',NULL,'eq_ref','UNQ_CUSTOMER_ADDRESS_ENTITY_VARCHAR_ENTITY_ID_ATTRIBUTE_ID,IDX_CUSTOMER_ADDRESS_ENTITY_VARCHAR_ATTRIBUTE_ID,IDX_CUSTOMER_ADDRESS_ENTITY_VARCHAR_ENTITY_ID,IDX_CUSTOMER_ADDRESS_ENTITY_VARCHAR_ENTITY_ID_ATTRIBUTE_ID_VALUE','UNQ_CUSTOMER_ADDRESS_ENTITY_VARCHAR_ENTITY_ID_ATTRIBUTE_ID','6','lazurd.at_default_billing.value,const','1','100.00','Using where'
'1','SIMPLE','at_company',NULL,'eq_ref','UNQ_CUSTOMER_ADDRESS_ENTITY_VARCHAR_ENTITY_ID_ATTRIBUTE_ID,IDX_CUSTOMER_ADDRESS_ENTITY_VARCHAR_ATTRIBUTE_ID,IDX_CUSTOMER_ADDRESS_ENTITY_VARCHAR_ENTITY_ID,IDX_CUSTOMER_ADDRESS_ENTITY_VARCHAR_ENTITY_ID_ATTRIBUTE_ID_VALUE','UNQ_CUSTOMER_ADDRESS_ENTITY_VARCHAR_ENTITY_ID_ATTRIBUTE_ID','6','lazurd.at_default_billing.value,const','1','100.00','Using where'
'1','SIMPLE','at_firstname',NULL,'eq_ref','UNQ_CUSTOMER_ENTITY_VARCHAR_ENTITY_ID_ATTRIBUTE_ID,IDX_CUSTOMER_ENTITY_VARCHAR_ATTRIBUTE_ID,IDX_CUSTOMER_ENTITY_VARCHAR_ENTITY_ID,IDX_CUSTOMER_ENTITY_VARCHAR_ENTITY_ID_ATTRIBUTE_ID_VALUE','UNQ_CUSTOMER_ENTITY_VARCHAR_ENTITY_ID_ATTRIBUTE_ID','6','lazurd.e.entity_id,const','1','100.00',NULL
'1','SIMPLE','at_lastname',NULL,'eq_ref','UNQ_CUSTOMER_ENTITY_VARCHAR_ENTITY_ID_ATTRIBUTE_ID,IDX_CUSTOMER_ENTITY_VARCHAR_ATTRIBUTE_ID,IDX_CUSTOMER_ENTITY_VARCHAR_ENTITY_ID,IDX_CUSTOMER_ENTITY_VARCHAR_ENTITY_ID_ATTRIBUTE_ID_VALUE','UNQ_CUSTOMER_ENTITY_VARCHAR_ENTITY_ID_ATTRIBUTE_ID','6','lazurd.e.entity_id,const','1','100.00',NULL
'1','SIMPLE','at_phone',NULL,'eq_ref','UNQ_CUSTOMER_ENTITY_VARCHAR_ENTITY_ID_ATTRIBUTE_ID,IDX_CUSTOMER_ENTITY_VARCHAR_ATTRIBUTE_ID,IDX_CUSTOMER_ENTITY_VARCHAR_ENTITY_ID,IDX_CUSTOMER_ENTITY_VARCHAR_ENTITY_ID_ATTRIBUTE_ID_VALUE','UNQ_CUSTOMER_ENTITY_VARCHAR_ENTITY_ID_ATTRIBUTE_ID','6','lazurd.e.entity_id,const','1','100.00',NULL

---

表結構：

CREATE TABLE `customer_entity_varchar` (
  `value_id` int(11) NOT NULL AUTO_INCREMENT COMMENT 'Value Id',
  `entity_type_id` smallint(5) unsigned NOT NULL DEFAULT '0' COMMENT 'Entity Type Id',
  `attribute_id` smallint(5) unsigned NOT NULL DEFAULT '0' COMMENT 'Attribute Id',
  `entity_id` int(10) unsigned NOT NULL DEFAULT '0' COMMENT 'Entity Id',
  `value` varchar(255) DEFAULT NULL COMMENT 'Value',
  PRIMARY KEY (`value_id`),
  UNIQUE KEY `UNQ_CUSTOMER_ENTITY_VARCHAR_ENTITY_ID_ATTRIBUTE_ID` (`entity_id`,`attribute_id`),
  KEY `IDX_CUSTOMER_ENTITY_VARCHAR_ENTITY_TYPE_ID` (`entity_type_id`),
  KEY `IDX_CUSTOMER_ENTITY_VARCHAR_ATTRIBUTE_ID` (`attribute_id`),
  KEY `IDX_CUSTOMER_ENTITY_VARCHAR_ENTITY_ID` (`entity_id`),
  KEY `IDX_CUSTOMER_ENTITY_VARCHAR_ENTITY_ID_ATTRIBUTE_ID_VALUE` (`entity_id`,`attribute_id`,`value`),
  CONSTRAINT `FK_CSTR_ENTT_VCHR_ATTR_ID_EAV_ATTR_ATTR_ID` FOREIGN KEY (`attribute_id`) REFERENCES `eav_attribute` (`attribute_id`) ON DELETE CASCADE ON UPDATE CASCADE,
  CONSTRAINT `FK_CSTR_ENTT_VCHR_ENTT_TYPE_ID_EAV_ENTT_TYPE_ENTT_TYPE_ID` FOREIGN KEY (`entity_type_id`) REFERENCES `eav_entity_type` (`entity_type_id`) ON DELETE CASCADE ON UPDATE CASCADE,
  CONSTRAINT `FK_CUSTOMER_ENTITY_VARCHAR_ENTITY_ID_CUSTOMER_ENTITY_ENTITY_ID` FOREIGN KEY (`entity_id`) REFERENCES `customer_entity` (`entity_id`) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB AUTO_INCREMENT=131094 DEFAULT CHARSET=utf8 COMMENT='Customer Entity Varchar';

Answer 1

截至目前，您的查詢是：

1. 首先執行所有左外部聯接。
2. 然后ORDER荷蘭國際集團的行。
3. 然后LIMIT行。

我將首先執行嚴格需要的外部聯接，然后進行排序和限制（以減少到20行），最后我將執行所有其余的外部聯接。 簡而言之，我會這樣做：

1. 首先執行最小的左外部聯接。 也就是說，只有兩個表。
2. 然后ORDER荷蘭國際集團的行。
3. 然后LIMIT行。 最多產生20行。
4. 執行所有其余的外部聯接。 此時，這不再是數千行，而只有20行。

此更改應大大減少“唯一鍵查找”的執行。 修改后的查詢將如下所示：

select
  e.*
  , `at_default_billing`.`value` AS `default_billing`
  , `at_billing_postcode`.`value` AS `billing_postcode`
  , `at_billing_city`.`value` AS `billing_city`
  , `at_billing_region`.`value` AS `billing_region`
  , `at_billing_country_id`.`value` AS `billing_country_id`
  , `at_company`.`value` AS `company`
  , `at_lastname`.`value` AS `lastname`
  , CONCAT(firstname
  , " "
  , at_lastname.value) AS `full_name`
  , `at_phone`.`value` AS `phone`
  , IFNULL(at_phone.value,"N/A") AS `telephone`
from ( -- Step #1: joining customer_entity with customer_entity_varchar
SELECT 
    `e`.*
    , `at_firstname`.`value` AS `firstname`
    , `e`.`entity_id` AS `id` 
FROM 
    `customer_entity` AS `e`  
LEFT JOIN 
    `customer_entity_varchar` AS `at_firstname` 
    ON (`at_firstname`.`entity_id` = `e`.`entity_id`) 
    AND (`at_firstname`.`attribute_id` = '5')  
ORDER BY -- Step #2: Sorting (the bare minimum)
    `at_firstname`.`value` ASC 
LIMIT 20 -- Step #3: Limiting (to 20 rows)
) e
LEFT JOIN -- Step #4: Performing all the rest of outer joins (only few rows now)
    `customer_entity_int` AS `at_default_billing` 
    ON (`at_default_billing`.`entity_id` = `e`.`entity_id`) 
    AND (`at_default_billing`.`attribute_id` = '13')  
LEFT JOIN 
    `customer_address_entity_varchar` AS `at_billing_postcode` 
    ON (`at_billing_postcode`.`entity_id` = `at_default_billing`.`value`)        
    AND (`at_billing_postcode`.`attribute_id` = '30')  
LEFT JOIN 
    `customer_address_entity_varchar` AS `at_billing_city` 
    ON (`at_billing_city`.`entity_id` = `at_default_billing`.`value`) 
    AND (`at_billing_city`.`attribute_id` = '26')  
LEFT JOIN 
    `customer_address_entity_varchar` AS `at_billing_region` 
    ON (`at_billing_region`.`entity_id` = `at_default_billing`.`value`) 
    AND (`at_billing_region`.`attribute_id` = '28')  
LEFT JOIN 
    `customer_address_entity_varchar` AS `at_billing_country_id` 
    ON (`at_billing_country_id`.`entity_id` = `at_default_billing`.`value`) 
    AND (`at_billing_country_id`.`attribute_id` = '27')  
LEFT JOIN 
    `customer_address_entity_varchar` AS `at_company` 
    ON (`at_company`.`entity_id` = `at_default_billing`.`value`) 
    AND (`at_company`.`attribute_id` = '24')  
LEFT JOIN 
    `customer_entity_varchar` AS `at_lastname` 
    ON (`at_lastname`.`entity_id` = `e`.`entity_id`) 
    AND (`at_lastname`.`attribute_id` = '7')  
LEFT JOIN 
    `customer_entity_varchar` AS `at_phone` 
    ON (`at_phone`.`entity_id` = `e`.`entity_id`) 
    AND (`at_phone`.`attribute_id` = '136')  

Answer 2

不幸的是， SELECT whole_mess_of_rows FROM many_tables ORDER BY one_col LIMIT small_number是一個臭名昭著的性能反模式。 為什么？ 因為它對很大的結果集進行排序，所以只丟棄其中的大部分。

訣竅是便宜地找出LIMIT small_number哪些行，然后僅從較大的查詢中檢索那些行。

您要哪幾行？ 在我看來，此查詢將檢索其customer_entity.id值。 但是很難確定，因此您應該測試此子查詢。

           SELECT customer_entity.entity_id
             FROM customer_entity
             LEFT JOIN customer_entity_varchar AS at_firstname 
                       ON (at_firstname.entity_id = e.entity_id) 
                      AND (at_firstname.attribute_id = '5') 
            ORDER BY at_firstname.value ASC
            LIMIT 20

這應該給出二十個相關的entity_id值。 測試一下。 查看其執行計划。 如果需要，向customer_entity添加適當的索引。 該索引可能是(firstname_attribute_id, firstname_entity_id, firstname_value)但我猜是這樣。

然后，可以將其放在主查詢的末尾，就在ORDER BY之前。

 WHERE e.entity_id IN (
           SELECT customer_entity.entity_id
             FROM customer_entity
             LEFT JOIN customer_entity_varchar AS at_firstname 
                       ON (at_firstname.entity_id = e.entity_id) 
                      AND (at_firstname.attribute_id = '5') 
            ORDER BY at_firstname.value ASC
            LIMIT 20
      )

而且事情應該快一點。

Answer 3

我同意前面的答案，但想強調更多反模式：過度規范化。

對於已經很糟糕的EAV模式，您的模式是一個奇怪的（且效率低下）的變體。

將customer_address_entity_varchar分成5個表幾乎沒有好處，也有一些缺點。 對於customer_entity_varchar同樣。

地址（通常）應作為幾列存儲在單個表中； 沒有JOINs到其他表。

同樣，對於名字+姓氏。

Phone可能是另一個問題，因為一個人/公司/實體可能有多個電話號碼（手機，家庭，工作，傳真等）。 但這是一個不同的故事。