慢速 SQL 带有排序依据的子查询的查询

Question

查询如下：

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的listing ID。子查询因 Order by 而变慢。我已经创建了索引，还需要5-6秒。

Table结构：

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

产品：存储产品变体（尺寸选项）

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

listing table:: 存储产品列表，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

显示每个列表和尺寸的最低价格。

Answer 1

由于您的子查询实际上没有做任何事情，请试试这个。如果这不起作用，post 解释语句的输出并避免使用 table 别名，如 'l' 和 'i'。真的很难读，而且出错的几率也增加了很多（比如，你因为某种原因自己加入了'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

我已经使用 Min(Price) 和 Group By Size 来获取最低价格列表。

查询性能从 5 秒提高到 0.5 秒

谢谢！

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