使用Order By的子查询缓慢SQL查询

Question

这是查询：

SELECT product.catalog_product_id AS catalog_id, listing.id AS listing_id, 
    product.size AS size, 0 AS amount, 
    listing.list_price AS price, 
    listing.created_at AS created_date 
FROM product
INNER JOIN listing ON listing.product_id = product.id 
WHERE product.catalog_product_id = XXXX
    AND listing.id = (
        SELECT l.id
        FROM listing l
        INNER JOIN product i ON l.product_id = i.id
        WHERE i.size = product.size AND i.catalog_product_id = XXXX
        ORDER BY l.list_price ASC, l.created_at ASC
        LIMIT 1
    ) 

子查询是获取最低价格的上市ID。使用Order by减慢子查询速度。我已经创建了索引，它仍然需要5-6秒。

表结构：

目录：这是主产品目录表

Catalog
-------
id
sku
name
description

产品：商店产品变型（尺寸选项）

Products
--------
id
catalog_id
size 

列表表::商店产品列表，一个产品尺寸选项可以有多个不同价格的产品列表。

listing
---------
id
product_id
list_price
created_at

输出：http://prntscr.com/kqh7fg

它显示每个列表和大小的最低价格。

Answer 1

由于您的子查询实际上没有做任何事情，请尝试这样做。如果这不起作用，请发布explain语句的输出，并避免使用像'l'和'i'这样的表别名。它真的很难阅读，错误的可能性增加很多（例如，你出于某种原因加入了'product.size'）。

SELECT
            product.catalog_product_id AS catalog_id,
            listing.id AS listing_id, 
            product.size AS size, 0 AS amount, 
            listing.list_price AS price, 
            listing.created_at AS created_date 
FROM        product
INNER JOIN  listing
    ON      listing.product_id = product.id 
WHERE       product.catalog_product_id = ?
ORDER BY    listing.list_price ASC,
            listing.created_at ASC
LIMIT       1

Answer 2

我能够解决这个问题。

SELECT product.catalog_product_id AS catalog_id, listing.id AS listing_id, 
product.size AS size,
listing.list_price AS price, 
listing.created_at AS created_date
FROM product
INNER JOIN listing ON listing.product_id = product.id
AND product.catalog_product_id = XXXX 
AND listing.id IN 
(
SELECT MIN(l.id)
FROM listing l
INNER JOIN product i ON l.product_id = i.id
WHERE i.catalog_product_id = XXXX 
AND list_price = (
SELECT MIN(list_price)
FROM listing l
INNER JOIN product it ON l.product_id = it.id
WHERE it.catalog_product_id = XXXX AND it.size = i.size
)
GROUP BY i.size
)

而不是使用：

ORDER BY l.list_price ASC, l.created_at ASC  LIMIT 1

我使用Min（Price）和Group By Size来获得最低价格。

查询性能从5秒提高到0.5秒

谢谢！