如何减少执行选择查询的时间

Question

减少运行时间（选择查询执行时间）
甚至查询都不起作用
正在减少代码行
有80张桌子

select 
     (ant_return_loss_pass='pass')+(ant_cross_isolation_pass='pass') as pass_count,
     (ant_return_loss_pass='fail')+(ant_cross_isolation_pass='fail') as fail_count,
     (ant_return_loss_pass='')    +(ant_cross_isolation_pass='') as blank_count
from 
(
  select A.serial_no,
         A.pass_fail as ant_return_loss_pass    
  from ant_return_loss A,
  (                                
      select max(register_date) as date
        from ant_return_loss 
        where 1=1
          and serial_no >= '184500074' 
          and serial_no <= '184500076' 
        group by serial_no
  ) B                                 
  where 1 = 1                     
    and A.register_date = B.date     
)AA
,(
  select A.serial_no,
         A.pass_fail as ant_cross_isolation_pass    
  from ant_cross_isolation A,
  (                                
      select  max(register_date) as date
        from ant_cross_isolation 
        where 1=1
          and serial_no >= '184500074' 
          and serial_no <= '184500076' 
        group by serial_no
  ) B                                 
  where 1 = 1                     
    and A.register_date = B.date     
)BB
where 1=1
  and AA.serial_no = BB.serial_no

不工作或工作600秒

Answer 1

以下查询使用显式联接语法和大小写表达式，使您的查询更易于理解：

ubuntu@ip-172-31-15-175:~$ vault status
Key                Value
---                -----
Seal Type          shamir
Initialized        true
Sealed             true
Total Shares       5
Threshold          3
Unseal Progress    0/3
Unseal Nonce       n/a
Version            1.0.0
HA Enabled         true
ubuntu@ip-172-31-15-175:~$

要检查它是否可以提高性能，但是需要访问您的数据库。例如，您为SELECT COUNT( CASE WHEN ant_return_loss_pass = 'pass' AND ant_cross_isolation_pass = 'pass' THEN 1 END ) AS pass_count , COUNT( CASE WHEN ant_return_loss_pass = 'fail' AND ant_cross_isolation_pass = 'fail' THEN 1 END ) AS fail_count , COUNT( CASE WHEN ant_return_loss_pass = '' AND ant_cross_isolation_pass = '' THEN 1 END ) AS blank_count FROM ( SELECT A.serial_no , A.pass_fail AS ant_return_loss_pass FROM ant_return_loss A INNER JOIN ( SELECT MAX( register_date ) AS date FROM ant_return_loss WHERE serial_no >= '184500074' AND serial_no <= '184500076' GROUP BY serial_no ) B ON A.register_date = B.date ) AA INNER JOIN ( SELECT A.serial_no , A.pass_fail AS ant_cross_isolation_pass FROM ant_cross_isolation A INNER JOIN ( SELECT MAX( register_date ) AS date FROM ant_cross_isolation WHERE serial_no >= '184500074' AND serial_no <= '184500076' GROUP BY serial_no ) B ON A.register_date = B.date ) BB ON AA.serial_no = BB.serial_no 还是ant_return_loss.serial_no编制索引将有助于子查询的where子句。

您是否对查询运行任何解释计划？参见：https://dev.mysql.com/doc/refman/5.7/en/explain.html

请注意，为避免运行时间过长，您可以在整个查询的各个部分上使用解释，寻找可能有帮助的索引：例如

ant_cross_isolation.serial_no

然后：

            explain
            SELECT MAX( register_date ) AS date
            FROM ant_return_loss
            WHERE serial_no >= '184500074'
            AND serial_no <= '184500076'
            GROUP BY serial_no

直到您检查完所有部分以提高性能为止。