How to find median by attribute with Postgres window functions?

Question

I use PostgreSQL and have records like this on groups of people:

name    | people | indicator
--------+--------+-----------
group 1 | 1000   | 1 
group 2 | 100           


        

Answer 1

Find the first cumulative sum of people greater than the median of total sum:

with the_data(name, people, indicator) as (
values
    ('group 1', 1000, 1),
    ('group 2', 100, 2),
    ('group 3', 2000, 3)
)
select name, people, indicator
from (
    select *, sum(people) over (order by name)
    from the_data
    cross join (select sum(people)/2 median from the_data) s
    ) s
where sum > median
order by name
limit 1;

  name   | people | indicator 
---------+--------+-----------
 group 3 |   2000 |         3
(1 row)