I used Postgresql 9.0.1.
Created a test table:
CREATE TABLE cum_sum_test ( id int, amt int);
Populate data:
INSERT INTO cum_sum_test SELECT c,c*100 from GENERATE_SERIES(1,10) as c;
Cumulative Sum Query:
SELECT id , amt, sum(amt) over (order by id) FROM cum_sum_test;
Result:
id | amt | sum
----+------+------
1 | 100 | 100
2 | 200 | 300
3 | 300 | 600
4 | 400 | 1000
5 | 500 | 1500
6 | 600 | 2100
7 | 700 | 2800
8 | 800 | 3600
9 | 900 | 4500
10 | 1000 | 5500
(10 rows)
