Date range in window functions PostgreSQL - postgresql

Question

I have a table with data for the whole of 2021 and 2022. I need to calculate the cumulative amount of the field by date for the previous year. For example, the row with date 2022-03-01 must have the value of the cumulative amount for 2021-03-01
I am trying this window function:
SUM(fact_mln) OVER(PARTITION BY date - INTERVAL '1 year' ORDER BY date)
But the method - INTERVAl '1 year' is not working
How can this window function be converted or is there any other solution?

Answer 1

You don't need PARTITION BY:
CREATE TABLE laurenz.amounts (
id integer GENERATED ALWAYS AS IDENTITY PRIMARY KEY,
date date NOT NULL,
fact_mln double precision NOT NULL
);
INSERT INTO amounts (date, fact_mln) VALUES
('2021-03-01', 1),
('2021-03-01', 2),
('2021-03-02', 3),
('2021-03-02', 4),
('2021-03-03', 5),
('2022-02-28', 6),
('2022-03-01', 7),
('2022-03-01', 8),
('2022-03-02', 9);
SELECT date, fact_mln,
sum(fact_mln) OVER (ORDER BY date
RANGE BETWEEN INTERVAL '1' YEAR PRECEDING
AND INTERVAL '1' YEAR PRECEDING)
FROM amounts;
date │ fact_mln │ sum
════════════╪══════════╪═════
2021-03-01 │ 1 │ ∅
2021-03-01 │ 2 │ ∅
2021-03-02 │ 3 │ ∅
2021-03-02 │ 4 │ ∅
2021-03-03 │ 5 │ ∅
2022-02-28 │ 6 │ ∅
2022-03-01 │ 7 │ 3
2022-03-01 │ 8 │ 3
2022-03-02 │ 9 │ 7
(9 rows)