Q:

Postgresql cumulative sum Last 3 days

I have this data and I want to compute a rolling 3-day  sum like below. 
Note: Missing date has to be considered.  So isn't just the last 3 rows, but 3 solar days. 

I tried with a window function but it's not working:
SELECT
    date,
    SUM(clicks) OVER (ORDER BY DATE ASC ROWS BETWEEN DATE - INTERVAL '3 day' AND date)
FROM table

A:

Upper bound should be current row and range:
SELECT
    date,
    SUM(clicks) OVER (ORDER BY DATE ASC range BETWEEN INTERVAL '3 day' PRECEDING AND CURRENT ROW)
FROM table

