Postgres 12

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create table my_table as
select v.*
from (values ('a', 1, 1, 1),
             ('b', 1, 1, 2),
             ('z', 1, 1, 3),
             ('z', 1, 1, 3),
             ('a', 1, 2, 1),
             ('b', 1, 2, 2),
             ('z', 1, 2, 3),
             ('z', 1, 2, 4)
             
     ) v(my_col, my_col2, my_col3, my_col4)

SELECT 8


select *,
       last_value(my_table.my_col) 
Over(Partition BY 
my_table.my_col2,
my_table.my_col3
Order By my_table.my_col4 
range BETWEEN 1 Following AND UNBOUNDED Following)
from my_table
order by 2, 3, 4


my_col
my_col2
my_col3
my_col4
last_value


a
1
1
1
z

b
1
1
2
z

z
1
1
3
null

z
1
1
3
null

a
1
2
1
z

b
1
2
2
z

z
1
2
3
z

z
1
2
4
null



SELECT 8


select my_table.*,
      (case when rank() over (partition by my_table.my_col2, my_table.my_col3
                        order by my_table.my_col4 desc)  > 1 
      then first_value(my_table.my_col) over (partition by my_table.my_col2, my_table.my_col3
                                   order by my_table.my_col4 desc
                                  )
 end)
from my_table
order by 2, 3, 4


my_col
my_col2
my_col3
my_col4
case


a
1
1
1
z

b
1
1
2
z

z
1
1
3
null

z
1
1
3
null

a
1
2
1
z

b
1
2
2
z

z
1
2
3
z

z
1
2
4
null



SELECT 8