Find and remove duplicate rows by two columns

Question

I read all the relevant duplicated questions/answers and I found this to be the most relevant answer:

INSERT IGNORE INTO temp(MAILING_ID,REPORT_ID) 
SELECT DISTI         


        

Answer 1

In a large data set if you are selecting the multiple columns in the select clause ex: select x,y,z from table1. And the requirement is to remove duplicate based on two columns:from above example let y,z then you may use below instead of using combo of "group by" and "sub query", which is bad in performance:

select x,y,z 
from (
select x,y,z , row_number() over (partition by y,z) as index_num
from table1) main
where main.index_num=1