mysql查询间歇返回空结果

我有一个查询，它有时在主机上返回一个空集，但在读取的复制副本上从不返回，并且在两个数据库上都有匹配的数据。这是随机的，我想知道是否有一个mysql设置或查询缓存的东西。在rds上运行mysql 5.6.40-log

我尝试过使用

optimizer\u switch=“index\u merge\u intersection=off”

，但没有成功

UPDATE optimizer\u switch=“index\u merge\u intersection=off似乎起到了作用，但我在进行此更改后清除了查询缓存，问题似乎自行解决了）。 发生的一个非常奇怪的问题是，查询在100%的时间内都是通过mysql命令行工作的；但直到我清除了查询缓存（即使它以同一用户的身份连接），web应用程序才工作。

一旦我对表

phppos_items

进行了优化，它会修复一点（3分钟），然后返回到不稳定状态（大部分是空集）。这些都是innodb表

设置：

似乎在一天的繁忙时间更经常返回空集。服务器是rds m4.L，有500个数据库，每个数据库有100个表

查询：

SELECT SUM( phppos_sales_items.damaged_qty ) AS damaged_qty, 
        SUM( phppos_sales_items.subtotal ) AS subtotal, 
        SUM( phppos_sales_items.total ) AS total, 
        SUM( phppos_sales_items.tax ) AS tax, 
        SUM( phppos_sales_items.profit ) AS profit
FROM  `phppos_sales` 
    JOIN  `phppos_sales_items` ON  `phppos_sales_items`.`sale_id` =  `phppos_sales`.`sale_id` 
    JOIN  `phppos_items` ON  `phppos_sales_items`.`item_id` =  `phppos_items`.`item_id` 
WHERE  `phppos_sales`.`deleted` =0
AND  `sale_time` BETWEEN  '2019-01-01 00:00:00' AND  '2019-12-31 23:59:59'
AND  `phppos_sales`.`location_id` IN ( 1 ) 
AND  `phppos_sales`.`store_account_payment` =0
AND  `suspended` <2
AND  `phppos_items`.`deleted` =0
AND  `phppos_items`.`supplier_id` = '485'
GROUP BY  `phppos_sales_items`.`sale_id` 

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您是否收到返回的错误代码或任何东西？您确定哪里的条件始终为真？这可能是隔离/序列化的问题吗？没有返回的错误代码，只有空的结果集。似乎只在一天的繁忙时间经常发生。哪里的条件始终为真MySQL错误参考是您是否收到返回的错误代码或任何东西？您确定哪里的条件始终为真吗？这可能是隔离/序列化的问题吗？没有返回错误代码，只有空的结果集。似乎只在一天的繁忙时间经常发生。哪里的条件始终为真MySQL错误参考是

+----+-------------+--------------------+-------------+-----------------------------------------------------------------------------------------------+-----------------------------+---------+-------------------------------------------------------+------+---------------------------------------------------------------------------------------------------------+
| id | select_type | table              | type        | possible_keys                                                                                 | key                         | key_len | ref                                                   | rows | Extra                                                                                                   |
+----+-------------+--------------------+-------------+-----------------------------------------------------------------------------------------------+-----------------------------+---------+-------------------------------------------------------+------+---------------------------------------------------------------------------------------------------------+
|  1 | SIMPLE      | phppos_items       | index_merge | PRIMARY,phppos_items_ibfk_1,deleted,deleted_system_item                                       | phppos_items_ibfk_1,deleted | 5,4     | NULL                                                  |   44 | Using intersect(phppos_items_ibfk_1,deleted); Using where; Using index; Using temporary; Using filesort |
|  1 | SIMPLE      | phppos_sales_items | ref         | PRIMARY,item_id,phppos_sales_items_ibfk_3,phppos_sales_items_ibfk_4,phppos_sales_items_ibfk_5 | item_id                     | 4       | phppoint_customer.phppos_items.item_id       |   16 | NULL                                                                                                    |
|  1 | SIMPLE      | phppos_sales       | eq_ref      | PRIMARY,deleted,location_id,sales_search,phppos_sales_ibfk_10                                 | PRIMARY                     | 4       | phppoint_customer.phppos_sales_items.sale_id |    1 | Using where                                                                                             |
+----+-------------+--------------------+-------------+-----------------------------------------------------------------------------------------------+-----------------------------+---------+-------------------------------------------------------+------+---------------------------------------------------------------------------------------------------------+
3 rows in set (0.00 sec)