加快緩慢3表MYSQL查詢

Question

我在查詢電子商務網站中的3個表。

訂單表：

id 
order_number 
name 
etc... 

ORDER_LINES表：

id 
order_number 
sku 
quantity 
etc. 

產品表

id 
sku 
title 
ship_by (INT) 
etc. 

order_number鏈接訂單表格至order_lines表。 SKU鏈接order_lines table to products table。

注意產品表中的ship_by列，這表示哪個供應商將運送該物品。查詢需要爲特定供應商提取訂單。訂單可能包含不同供應商出售的物品。

這是我好不容易纔湊齊查詢：

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 

它走大約7秒鐘執行查詢。

如果我從第二個SELECT查詢中刪除行'AND order_lines.order_number = orders.order_number'，它幾乎立即執行，但是沒有這一行，它不能正常工作，因爲我需要它。

除了將'ship_by'列添加到order_lines表（我寧願不做，因爲我不得不改變很多php代碼），有沒有辦法修改這個查詢來加速它？

該查詢是從PHP外部運行的，因此它必須是純粹的mysql查詢。

這裏是EXPLAIN的查詢：

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 

感謝

Answer 1

你order_lines表需要上order_number指數至少是。我們需要查看模式以最好地選擇一個模式。也許一個綜合指數會在其他領域加快速度。

但是在選擇索引更改時，必須仔細權衡系統中的其他查詢以及對插入和更新速度的影響。

的目標不應該是使你的應用程序快10％，在90的

費用要顯示非常有用的信息，發佈show create table tableName爲相關的表名。 （而不是用手描述它，就像我的桌子上有這個那樣）。我們需要查看訂單，訂單，產品的模式。

上Create Index

Answer 2

手冊頁面，您可以用exists替換子查詢：

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，您查詢的片斷沒有在外部查詢使用order_lines。我懷疑你可以擺脫它與聚合：

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 
     . . . 

這至少會返回所有的訂單信息 - 和缺乏聚集可以簡化查詢的其他部分。如果某些版本的查詢運行得很快，那麼索引可能是合理的。

Answer 3

Idk表格在你的內聯視圖中有多大，但是如果它很大，那麼它可以幫助使用聯合，而不必爲每個記錄查詢視圖。

有點像。

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