Hi,
Back in the old days they said that you should never use select distinct from a database, because the optimizer cannot use index. I want to know if it is some difference in performance between:
select distinct *
with cte as(
select col1,
row_number() over (partition by col1 order by col1) as DuplicateCount
from table1
)
select col1 from cte where DuplicateCount = 1;
select col1
from table1
group by col1
Maybe it is another way to write an sql statement with best performance regarding select distinct values from on one or more columns.