sql优化问题，如何创建索引

Question

现有如下sql,每次查询将近一分钟，如何为该sql创建索引

SELECT e.value,p.point_name,e.save_time FROM ep_data_11618820768178833_ANA_202106 e,ep_point p
WHERE e.data_attribute in(SELECT data_attribute FROM ep_point WHERE point_name='WZAI205')
and e.one_level in (SELECT one_level FROM ep_point WHERE point_name='WZAI205')
and e.two_level in (SELECT two_level FROM ep_point WHERE point_name='WZAI205')
and e.three_level in (SELECT three_level FROM ep_point WHERE point_name='WZAI205')
and p.point_name='WZAI205'
and e.save_time='2021-6-11 18:00:00'
UNION
SELECT e.value,p.point_name,e.save_time FROM ep_data_11618820768178833_ANA_202106 e,ep_point p
WHERE e.data_attribute in(SELECT data_attribute FROM ep_point WHERE point_name='WZAI205')
and e.one_level in (SELECT one_level FROM ep_point WHERE point_name='WZAI205')
and e.two_level in (SELECT two_level FROM ep_point WHERE point_name='WZAI205')
and e.three_level in (SELECT three_level FROM ep_point WHERE point_name='WZAI205')
and p.point_name='WZAI205'
and e.save_time='2021-6-11 09:00:00'

ep_data_11618820768178833_ANA_202106 表结构

ep_point 表结构

Answer 1

这个查询语句要优化一下，尽量不要使用 in 用连接查询

save_time 条件放最前面