[英]MySQL subquery optimisation
我在這里的最小視圖中有 4 個表:
銷售量:
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
銷售_付款:
id
**sales_id**
payment_amount
payment_change
payment_method
產品:
id
product_name
我有一個查詢,它可以即時計算折扣並報告它。 這在記錄總數低於 100-200k 的情況下非常有效。 但是隨着數量的增加,花費的時間真的很慢。 我想這是因為我使用的子查詢。 任何人都可以對此有所了解。 每個表上都有一個 client_id 和 outlet_id,用於將它們與系統中的其他用戶區分開來。
目前這些表有 1-3 百萬行,有問題的客戶端有 300k-600k。 查詢需要 30+ 秒。 對於行數較少的其他人,甚至可以在亞秒內獲得它。 帶星號的是索引。 如何改進查詢以獲得相同的預期結果? 我現在的查詢:
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
更新:
回答@rick-james 的問題
它在 Amazon Aurora 上運行,內存為 15GB。
銷售表:0.5GB 數據 1.3GB 索引
銷售項目:1.3GB 數據 3.2GB 索引
銷售付款:0.5GB 數據 1.1GB 索引
所有表的整理都是 utf8_unicode_ci。
ID select_type 表類型 possible_keys 鍵 key_len ref 行過濾額外
1 PRIMARY sales 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 const 5352 使用索引條件; 使用哪里; 使用臨時; 使用文件排序
1 主要參考 108 MyDB.sales.id 10
1 主要參考 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 const 5092 使用索引條件; 使用哪里; 使用臨時; 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 const 13340 使用索引條件; 使用哪里; 使用臨時; 使用文件排序
2 衍生產品 eq_ref PRIMARY,products_id_unique PRIMARY 108 MyDB.sales_items.product_id 1
任何其他方式來重寫查詢以獲得所需的結果?
ORDER BY
與GROUP BY
ORDER BY
不必要地不同時,需要額外的排序過程。LEFT JOIN ( SELECT ... )
在至少 5.6 之前效率極低。 請提供EXPLAIN SELECT ...
以查看它是否已優化。 你用的是什么版本?LEFT JOIN ( SELECT ... ) LEFT JOIN ( SELECT ... )
。 補充:因為我沒有看到“自動鍵”,這很糟糕。 這讓我懷疑它是否真的是 MySQL 5.6。PRIMARY KEY
包括 client_id、outlet_id、order_status 和 sale_HOUR。SHOW CREATE TABLE
輸出; 您對表的描述中缺少很多細節——索引、數據類型、大小、排序規則等。補充:仍然需要這個; 還有一些事情需要檢查。 一個可能的解決方案:使用兩個LEFT JOIN SELECTs
每一個CREATE TEMPORARY TABLE
; 然后使用它們。
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