Question

我在电子商务网站查询3个表格。

订单表：

id
order_number
name
etc...

order_lines表：

id
order_number
sku
quantity
etc.

产品表

id
sku
title
ship_by (INT)
etc.

order_number 将订单表链接到 order_lines 表。 SKU 将 order_lines 表链接到产品表。

请注意产品表中的 ship_by 列，这表示将向哪个供应商发货。查询需要为特定供应商提取订单。订单可能包含不同供应商销售的商品。

这是我设法凑齐的查询：

SELECT 
    orders.`order_number`               as `orderId`,
    orders.`shipping`                   as `fPostageCost`,
     FROM_UNIXTIME(orders.`time`)       as `dReceievedDate`,
    (
    CASE orders.`dob`
    WHEN 'COURIER 3 DAY' THEN 'UK_SellersStandardRate'
    WHEN 'COURIER 24 HOUR' THEN 'UK_OtherCourier24'
    ELSE orders.`dob`
    END
    )                       
    ...(plus a number more)

 FROM orders
 INNER JOIN order_lines
 ON   orders.order_number = order_lines.order_number
 WHERE 
       ( 
         (SELECT COUNT(order_lines.sku) 
          FROM order_lines, products 
          WHERE order_lines.sku = products.sku 
          AND products.ship_by = 1 
          AND order_lines.order_number = orders.order_number) > 0 
       )
       AND ( orders.`printed` = 'N' OR orders.`printed` IS NULL )
       AND orders.status = 'Awaiting Despatch'
       AND ( orders.payment_status = 'Success' OR orders.payment_status = 'Paypal Paid' OR orders.payment_status = 'Manual Payment' )
  GROUP BY orders.`order_number`
  ORDER BY orders.order_number ASC

执行查询大约需要7秒钟。

如果我删除了行＆＃39; AND order_lines.order_number = orders.order_number＆＃39;从第二个SELECT查询开始，它几乎立即执行，但如果没有这一行，它就不会像我需要的那样工作。

除了添加＆＃39; ship_by＆＃39;列到order_lines表（由于我不得不改变很多php代码，我不愿意这样做），有没有办法修改这个查询以加快它的速度？

查询是从PHP外部运行的，所以它必须是一个纯粹的mysql查询。

以下是查询的EXPLAIN：

id  select_type         table        type     possible_keys     key         key_len     ref                                     rows    Extra
1   PRIMARY             order_lines  ALL      NULL              NULL        NULL        NULL                                    9627    Using temporary; Using filesort
1   PRIMARY             orders       eq_ref   order_idx         order_idx   17          .order_lines.order_number   1       Using where
2   DEPENDENT SUBQUERY  order_lines  ALL      NULL              NULL        NULL        NULL                                    9627    Using where
2   DEPENDENT SUBQUERY  products     ref      sku_2,sku,sku_3   sku_2       63          order_lines.prod_code   11      Using where

由于

Answer 1

您的order_lines表至少需要order_number上的索引。我们需要查看架构以便最好地选择一个架构。也许复合指数会在其他领域加快速度。

但是在选择索引更改时，必须仔细权衡系统中的其他查询，以及对插入和更新速度的影响。

目标不应该是以90％为代价快速制作10％的应用程序。

要显示非常有用的信息，请发布show create table tableName相关的表名。（而不是自由地描述它，就像我的桌子有这个和那个）。我们需要查看订单，订单行，产品的架构。

Create Index

上的手册页

Answer 2

Idk表格在您的内联视图中有多大，但如果它很大则表示它可能有助于使用联合而不必查询每个记录的视图。

类似的东西。

    SELECT L1*
FROM 
(SELECT 
    orders.`order_number`               as `orderId`,
    0                                   AS  SKU_CNT,
    orders.`shipping`                   as `fPostageCost`,
     FROM_UNIXTIME(orders.`time`)       as `dReceievedDate`,
    (
    CASE orders.`dob`
    WHEN 'COURIER 3 DAY' THEN 'UK_SellersStandardRate'
    WHEN 'COURIER 24 HOUR' THEN 'UK_OtherCourier24'
    ELSE orders.`dob`
    END
    )                       
    ...(plus a number more)

 FROM orders
 INNER JOIN order_lines
 ON   orders.order_number = order_lines.order_number
 WHERE  ( orders.`printed` = 'N' OR orders.`printed` IS NULL )
       AND orders.status = 'Awaiting Despatch'
       AND ( orders.payment_status = 'Success' OR orders.payment_status = 'Paypal Paid' OR orders.payment_status = 'Manual Payment' )


 UNION ALL
    Select
    0                       AS  ORDERID,
    COUNT(OL.SKU)           AS  SKU_CNT,
    0                       as `fPostageCost`,
    NULL                    as `dReceievedDate`,
    ...
    FROM ORDER_LINES OL,
         PRODUCTS PR
    WHERE order_lines.sku = products.sku 
          AND products.ship_by = 1 
          AND order_lines.order_number = orders.order_number     
    GROUP BY ORDERID, ORDER_LINES_CNT, fPostageCost`, dReceievedDate`,
)L1
WHERE L1.SKU_CNT > 0
GROUP BY L1.`order_number`
ORDER BY L1.order_number ASC

Answer 3

您可以将子查询替换为exists：

WHERE EXISTS (SELECT 1
              FROM order_lines ol2 JOIN
                   products p2
                   ON ol2.sku = p.sku AND
                      p2.ship_by = 1 
                      ol.order_number = o.order_number
             ) AND
        . . .

但是，您的查询片段未在外部查询中使用order_lines。我怀疑你可以通过聚合摆脱它：

FROM orders o
WHERE EXISTS (SELECT 1
              FROM order_lines ol2 JOIN
                   products p2
                   ON ol2.sku = p2.sku AND
                      p2.ship_by = 1 
                      ol.order_number = o.order_number
             ) AND
        . . .

这将至少返回所有订单信息 - 并且缺少聚合可能会简化查询的其他部分。如果某些版本的查询运行得很快，那么索引可能设置得合理。

加快慢速3表MYSQL查询

3 个答案: