kql window query sum over partition

Question

I have the following table :

Group	UserId	count_
1	2	2
1	1	3
2	3	3
2	4	7

I want to run a sum() over partition by group in order to calculate the total requests for every group and add a percentage column for every user in the group.

The expected output :

Group	UserId	percent
1	2	0.4
1	1	0.6
2	3	0.3
2	4	0.7

In SQL i would do something like the following :

select group,user,count_/sum(count_) over(partition by group) from table

How can i get this output ?

Answer 1

At least at this point, a JOIN is needed (similarly to a SQL solution without the use of windows functions)

let t = datatable(Group:int, UserId:int, count:int)
[
    1 ,2 ,2
   ,1 ,1 ,3
   ,2 ,3 ,3
   ,2 ,4 ,7
];
t
| summarize sum(['count']) by Group
| join kind=inner t on Group 
| project Group, UserId, percent = 1.0*['count']/sum_count

Group	UserId	percent
1	2	0.4
1	1	0.6
2	3	0.3
2	4	0.7

Fiddle