MySQL UNION Sub Select很慢

Question

我有6张桌子

1. 表a_orders = 41915行。
2. 表a_orders_items = 77765行。
3. 表a_orders_items_history = 379611行。
4. 表b_orders = 743032行。
5. 表b_orders_items = 984839行。
6. 表b_orders_items_history = 5685609行。

我想通过过滤订单日期和订单状态来获取订单数据，所以，我有这样的查询：

 SELECT orders_id, item_id, qty, status, order_date FROM ( (SELECT bo.orders_id AS orders_id, boi.orders_items_id AS item_id, boi.order_quantity AS qty, boish.status AS status, bo.import_date AS order_date FROM b_orders bo LEFT JOIN b_orders_items boi ON boi.orders_id = bo.orders_id LEFT JOIN b_orders_items_history boih ON boih.orders_items_id = boi.orders_items_id WHERE bo.partner_id IN (2,10) AND DATE(boish.status_date) >= DATE('2015-10-27') AND DATE(boish.status_date) <= DATE('2016-04-26') AND boish.status = 10 GROUP BY boish.status_date, boish.status) UNION ALL (SELECT ao.orders_id AS orders_id, aoi.orders_products_id AS item_id, aoi.products_quantity AS qty, opsh.status AS status, ao.date_purchased AS order_date FROM a_orders ao LEFT JOIN a_orders_items aoi ON aoi.orders_id = ao.orders_id LEFT JOIN a_orders_items_history aoih ON aoih.orders_products_id = aoi.orders_products_id WHERE DATE(aoih.status_date) >= DATE('2015-10-27') AND DATE(aoih.status_date) <= DATE('2016-04-26') AND aoih.status = 10 GROUP BY aoih.status_date, aoih.status) ) temp_table GROUP BY item_id, status; 

它花了5秒钟完成，并且mysql慢查询也被记录下来。 我有什么可以做得更快？ 我已经尝试过使用UNION，并将其放置在WHERE过滤器的子查询之外，但是结果是相同的。

编辑：我将在此处显示解释结果：

      id | select_type | table | type | possible_keys | key | key_len | ref | rows | extra

1|PRIMARY|<derived2>|ALL|null|null|null|null|3385|Using temporary; Using filesort
2|DERIVED|bo|ALL|PRIMARY,customer_billing_id,customer_shipping_id|null|null|null|743032|Using where; Using temporary; Using filesort
2|DERIVED|boi|ref|PRIMARY,Index_Orders|Index_Orders|4|bo.bo_orders_id|1|Using where
2|DERIVED|boih|ref|orders_items_id|orders_items_id|5|boi.orders_items_id|1|Using where
3|UNION|aoi|ALL|PRIMARY,orders_id|null|null|null|77765|Using temporary; Using filesort
3|UNION|ao|eq_ref|PRIMARY|PRIMARY|4|aoi.orders_id|1|empty
3|UNION|aoih|ref|orders_products_id|orders_products_id|5|aoi.orders_products_id|1|Using where
null|UNION RESULT|<union2,3>|ALL|null|null|null|null|null|empty

谢谢，任何帮助表示赞赏。

Answer 1

您可以尝试解释您的查询，这将为您提供有关查询的索引用法的信息。您可以在MySQL文档中找到它。

http://dev.mysql.com/doc/refman/5.7/en/explain.html