Question

我有以下查询：

SELECT  p2c.pid AS productNumber,
        p.name AS productName
    ,   (
            SELECT COUNT(*)
            FROM   products2customers
            WHERE  pid = p2c.pid
        ) AS registered
    ,   (
            SELECT COUNT(*)
            FROM   products2customers
            WHERE  pid = p2c.pid
               AND date_add(from_unixtime(purchased), INTERVAL 5 YEAR) >= CURDATE()
        ) AS inWarranty
    ,   (
            SELECT COUNT(*)
            FROM   products2customers
            WHERE  pid = p2c.pid
               AND date_add(from_unixtime(purchased), INTERVAL 5 YEAR) < CURDATE()
        ) AS outOfWarranty
    ,   (
            SELECT DATE_FORMAT( MAX( from_unixtime(purchased) ), '%d.%m.%Y')
            FROM   products2customers
            WHERE  pid = p2c.pid
        ) AS lastPurchased
    ,   (
            SELECT DATE_FORMAT( date_add( MAX( from_unixtime(purchased) ), INTERVAL 5 YEAR), '%d.%m.%Y')
            FROM   products2customers
            WHERE  pid = p2c.pid
        ) AS warrantyUntil
FROM    (
            SELECT DISTINCT
                p2c.pid
            FROM
                products2customers p2c
        ) AS p2c
JOIN
    products p
ON
    p.id = p2c.pid
ORDER BY
    inWarranty DESC

查询在数据库表上执行，该表有25.000行。此查询的执行时间约为40秒。结果将显示在网页上，因此等待40秒以获得结果并不是那么好。

有没有办法执行此查询并保存输出？因为如果每晚都执行此查询就足够了。

这样做的最佳方式是什么？我应该创建一个cronjob并执行此查询并将结果写入数据库吗？或者有更好的方法吗？

或者我可以优化此查询，以使其更快？

Answer 1

我认为所有相关的子查询都在扼杀你。试试这个：

SELECT  p2c.pid AS productNumber,
        p.name AS productName,
        COUNT(*) AS registered,
        SUM(date_add(from_unixtime(purchased), INTERVAL 5 YEAR) >= CURDATE()) AS inWarranty,
        SUM(date_add(from_unixtime(purchased), INTERVAL 5 YEAR) < CURDATE()) AS outOfWarranty,
        DATE_FORMAT( MAX( from_unixtime(purchased) ), '%d.%m.%Y') AS lastPurchased,
        DATE_FORMAT( date_add( MAX( from_unixtime(purchased) ), INTERVAL 5 YEAR), '%d.%m.%Y') AS warrantyUntil
FROM products2customers p2c
JOIN products p ON p.id = p2c.pid
GROUP BY p2c.pid
ORDER BY inWarranty DESC

Answer 2

可以从Explain Plan开始，看看是否可以通过创建索引来加速任何部分。

Answer 3

把它放到一个cron作业中：

CREATE TABLE products_warrany SELECT p2c.pid AS productNumber, ...

稍后使用以下查询而不是原始的长查询：

SELECT * FROM products_warrany ORDER BY ...

您还可以运行其他过滤，排序等功能。 Reference.

如何处理大型mysql查询

3 个答案: