MySQL的子查询优化

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销售：

id 
has_discount 
discount_is_percentage 
discount_amount 
**sale_date_time** 
**order_status**

Sales_items：

id 
**sales_id** 
has_discount 
discount_is_percentage 
discount_amount 
**product_id** (This can sometimes be null) 
price_inc_vat_per_item 
quantity 
vat_rate 
is_removed

Sales_payments：

id 
**sales_id** 
payment_amount 
payment_change 
payment_method

产品：

id 
product_name

我有一个查询，它可以即时计算折扣并报告。这在记录总数低于100-200k的情况下效果很好。但随着人数的增加，所花的时间非常缓慢。我想这是因为我使用的子查询。任何人都可以为此发光。每个表上有一个client_id和outlet_id，可以将它们与系统中的其他用户区分开来。

目前这些表格有1到3百万行，有问题的客户端有300k-600k。查询需要30多秒。对于行数较少的其他人，甚至可以在几秒钟内得到它。有星星的是指数。如何改进查询以获得相同的预期结果？查询我现在有：

SELECT DATE_FORMAT(CONVERT_TZ(sales.sale_date_time,'UTC','Europe/London'), 
       '%l%p') as title, count(*) as total_sales, SUM(sales_items.quantity 
        ) as total_quantities, 
     SUM(sales_items.price_before_line_discount) as price_before_line_discount, 
     SUM(sales_items.price_before_line_discount-sales_items.line_discount) as price_after_line_discount, 
     SUM(sales_items.vat_rated_sales) as vat_rated_sales_before_discount, 
     SUM(sales_items.zero_rated_sales) as zero_rated_sales_before_discount, 
     SUM(sales_items.total_vat_only) as total_vat_only_before_discount, 
     SUM(sales_payments.payment_taken) as payment_taken, SUM(sales_items.line_discount) as total_line_discount, 
     SUM(sales_payments.payment_cash) as payment_cash, SUM(CASE WHEN sales.has_discount=1 
       AND sales.discount_is_percentage=0 THEN sales.discount_amount WHEN sales.has_discount=1 
       AND sales.discount_is_percentage=1 THEN ((sales_items.price_before_line_discount-sales_items.line_discount)*sales.discount_amount/100) WHEN sales.has_discount=0 THEN 0 END 
      )as total_sales_discount, 
     SUM(CASE WHEN sales.has_discount=1 THEN CASE WHEN discount_is_percentage=0 THEN (sales_items.vat_rated_sales*sales.discount_amount)/(sales_items.price_before_line_discount-sales_items.line_discount) WHEN discount_is_percentage=1 THEN (sales_items.vat_rated_sales*((sales_items.price_before_line_discount-sales_items.line_discount)*sales.discount_amount/100))/(sales_items.price_before_line_discount-sales_items.line_discount) END ELSE 0 END)as vat_rated_sales_discount, 
     SUM(CASE WHEN sales.has_discount=1 THEN CASE WHEN discount_is_percentage=0 THEN (sales_items.zero_rated_sales*sales.discount_amount)/(sales_items.price_before_line_discount-sales_items.line_discount) WHEN discount_is_percentage=1 THEN ((sales_items.zero_rated_sales*((sales_items.price_before_line_discount-sales_items.line_discount)*sales.discount_amount/100))/(sales_items.price_before_line_discount-sales_items.line_discount)) END ELSE 0 END)as zero_rated_sales_discount, 
     SUM(CASE WHEN sales.has_discount=1 THEN CASE WHEN discount_is_percentage=0 THEN (sales_items.total_vat_only*sales.discount_amount)/(sales_items.price_before_line_discount-sales_items.line_discount) WHEN discount_is_percentage=1 THEN (sales_items.total_vat_only*((sales_items.price_before_line_discount-sales_items.line_discount)*sales.discount_amount/100))/(sales_items.price_before_line_discount-sales_items.line_discount) END ELSE 0 END)as total_vat_only_discount 
    FROM `sales` 
    left join 
    (
     SELECT sales_id, SUM(quantity) as quantity, SUM(price_inc_vat_per_item*quantity) AS price_before_line_discount, 
       SUM(CASE WHEN has_discount=1 
         AND discount_is_percentage=0 THEN discount_amount WHEN has_discount=1 
         AND discount_is_percentage=1 THEN ((price_inc_vat_per_item*quantity)*discount_amount/100) WHEN has_discount=0 THEN 0 END 
        )as line_discount, 
       SUM(CASE WHEN vat_rate>0 THEN CASE WHEN has_discount=1 
         AND discount_is_percentage=0 THEN ((price_inc_vat_per_item*quantity)-discount_amount) WHEN has_discount=1 
         AND discount_is_percentage=1 THEN ((price_inc_vat_per_item*quantity)-((price_inc_vat_per_item*quantity)*discount_amount/100)) WHEN has_discount=0 THEN (price_inc_vat_per_item*quantity) END ELSE 0 END 
        )as vat_rated_sales, 
       SUM(CASE WHEN vat_rate=0 THEN CASE WHEN has_discount=1 
         AND discount_is_percentage=0 THEN ((price_inc_vat_per_item*quantity)-discount_amount) WHEN has_discount=1 
         AND discount_is_percentage=1 THEN ((price_inc_vat_per_item*quantity)-((price_inc_vat_per_item*quantity)*discount_amount/100)) WHEN has_discount=0 THEN (price_inc_vat_per_item*quantity) END ELSE 0 END 
        )as zero_rated_sales, 
       SUM(CASE WHEN vat_rate>0 THEN CASE WHEN has_discount=1 
         AND discount_is_percentage=0 THEN ((price_inc_vat_per_item*quantity)-discount_amount)-((price_inc_vat_per_item*quantity)-discount_amount)/(1+(vat_rate/100)) WHEN has_discount=1 
         AND discount_is_percentage=1 THEN ((price_inc_vat_per_item*quantity)-((price_inc_vat_per_item*quantity)*discount_amount/100))-((price_inc_vat_per_item*quantity)-((price_inc_vat_per_item*quantity)*discount_amount/100))/(1+(vat_rate/100)) WHEN has_discount=0 THEN (price_inc_vat_per_item*quantity)-(price_inc_vat_per_item*quantity)/(1+(vat_rate/100)) END ELSE 0 END 
        )as total_vat_only 
      FROM sales_items 
      WHERE client_id='0fe26d93-775f-440c-a119-13cbcb6cbc0c' 
       AND is_removed=0 
      GROUP BY sales_id 
    ) as sales_items ON `sales`.`id` = `sales_items`.`sales_id` 
    left join 
    (
     SELECT sales_id, SUM(payment_amount-payment_change) payment_taken, 
       SUM(CASE WHEN payment_method='CASH' THEN (payment_amount-payment_change) ELSE 0 END) as payment_cash 
      FROM sales_payments 
      WHERE client_id='0fe26d93-775f-440c-a119-1396c36cbc0c' 
      GROUP BY sales_id 
    ) as sales_payments ON `sales`.`id` = `sales_payments`.`sales_id` 
    WHERE `sales`.`client_id` = '0fe26d93-775f-440c-a119-1396c36cbc0c' 
     and `sales`.`outlet_id` = 'd5b74bdf-5cef-4455-bf99-13cbcb6cbc0c' 
     and `sales`.`order_status` = 'COMPLETED' 
     and `sale_date_time` >= '2016-01-28 00:00:00' 
     and `sale_date_time` <= '2016-11-28 23:59:00' 
    GROUP BY HOUR(CONVERT_TZ(sales.sale_date_time,'UTC','Europe/London')) 
    ORDER BY `sale_date_time` ASC

UPDATE：

要回答@里克 - 詹姆斯

我需要sale_date_time这是一个时间字段进行排序的问题有关。小组需按小时报告。它也有天，月 - 年等取决于所查询的时期。因为设计原因不得不使用UUID。整个数据库大约8GB，其中大部分都是这四张表。由于我有很多外键约束，索引长度比实际数据大小要大。

这是在亚马逊极光与15GB内存。

销售表： 0.5GB数据1.3GB指数

销售项目： 1.3GB数据3.2GB指数

销售款项： 0.5GB数据1.1GB指数

所有表核对是utf8_unicode_ci。

它使用的是Aurora 5.6，它是MySQL 5.6。这里是解释选择。

ID SELECT_TYPE表键入possible_keys键key_len REF行过滤额外

1主销售REF sales_client_id_outlet_id_foreign，sales_client_id_index，sales_outlet_id_index，sales_sale_date_time_index，sales_order_status_index sales_client_id_index 108常量5352使用指数条件;在哪里使用;使用临时;使用文件排序

1 PRIMARY REF 108 MyDB.sales.id 10

1 PRIMARY REF 108 MyDB.sales.id 10

3 DERIVED sales_payments REF sales_payments_client_id_outlet_id_foreign，sales_payments_client_id_index sales_payments_client_id_outlet_id_foreign 108常量5092使用索引条件;在哪里使用;使用临时;使用文件排序

2 DERIVED sales_items REF sales_items_client_id_outlet_id_foreign，sales_items_client_id_index sales_items_client_id_outlet_id_foreign 108常量13340使用指数条件;在哪里使用;使用临时;使用文件排序

2衍生产品eq_ref PRIMARY，products_id_unique PRIMARY 108 MyDB.sales_items.product_id 1

可能会考虑将结果存储在数据库，并从那里得到的。唯一的问题是旧订单可以修改，如果发生这种情况，总数将需要重建。

任何其他方式来重写查询以获得所需的结果？

来源

2017-01-13 James

当ORDER BY与GROUP BY不必要地不同时，需要额外的排序传递。
当数据大于可以缓存在RAM中时，UUID效率非常低。桌子有多大？ `innodb_buffer_pool_size的价值是什么？你有多少RAM？
LEFT JOIN (SELECT ...)直到5.6时效率非常低。请提供EXPLAIN SELECT ...以查看它是否已优化。你使用什么版本？
更糟糕的是LEFT JOIN (SELECT ...) LEFT JOIN (SELECT ...)。 加入：由于我没有看到“自动密钥”，这是不好的。它让我怀疑它是否真的是MySQL 5.6。
构建和维护“汇总表”可能是最终的答案。它可能会有PRIMARY KEY，包括client_id，outlet_id，order_status和sale_HOUR。
是否子查询本身运行缓慢？如果是这样，请单独提问以专注于子查询。请提供SHOW CREATE TABLE的输出;你的表格描述中缺少很多细节 - 索引，数据类型，大小，排序规则等。加：仍然需要这个;还有一些事情要检查。一个可能的解决方案：CREATE TEMPORARY TABLE与两个LEFT JOIN SELECTs中的每一个;然后使用它们。

来源

2017-01-13 20:00:00

请参阅最新的问题。 – James

参见已添加...... –

对不起，它在派生表上有。所以刚刚从粘贴的代码中剥离了它。我会尝试使用临时表方法来查看是否有所改进。 – James

MySQL的子查询优化

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