[QUESTION] Window function with partition by and order by

Hello,

While looking at aggregates in window function, I found something
unusual and would be glad I could get some clarification.

Consider following table (mytable):

id, name

1, A

1, A

2, B

3, A

1, A

select *, avg(id) over (partition by name, order by id) from mytable;

Output:

id, name, avg

1, A, 1

1, A, 1

1, A, 1

3, A, 1.5

2, B, 2

Question is: Average of id for partition name (A) should be 6/4 = 1.5
for all rows in that partition but this result is seen only at the last
one row in partition (A). Am I missing here something?

Thanks

--
Regards,
Ankit Kumar Pandey