线上问题集锦(2)

mysql and 和 or为什么会导致性能差别巨大？

select t1.* from t_user t1,   t_student_info t2  where t1.user_unique_code = t2.uu_id   
and 
( t1.user_name like '%谭%'  or  t2.student_no like '%谭%'  or  t2.company like '%谭%'  ) 
ORDER BY t1.create_time desc 

select t1.* from t_user t1,   t_student_info t2  where t1.user_unique_code = t2.uu_id   
or 
( t1.user_name like '%谭%'  or  t2.student_no like '%谭%'  or  t2.company like '%谭%'  ) 
ORDER BY t1.create_time desc 

openfeign get转post的问题

openfeign @RequestBody+Get。 默认会转成post提交。

发送邮件报错 connet failure Could not connect to SMTP host: smtpdm.aliyun.com, port: 465, response: -1

将端口改为80或25时可以正常发送，没有任何问题，所以问题在于使用465端口时 SSL 的配置出错了，添加了以下配置后问题解决：

spring.mail.properties.mail.smtp.ssl.enable=true