This page is a quick reference checkpoint for SUM OVER in Snowflake: behavior, syntax rules, edge cases, and a minimal example; plus the official vendor documentation.
SUM OVER returns the running or partitioned sum within the window frame.
When used as a window function with an ORDER BY clause, the implied default window frame is RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW. Additionally: the DISTINCT keyword is prohibited in the window-function form. NULLs are ignored (if all are NULL then result is NULL).
If this behavior feels unintuitive, the tutorial below explains the underlying pattern step-by-step.
SUM([ DISTINCT ] <expr1>) OVER ( [ PARTITION BY <expr2> ] [ ORDER BY <expr3> [ ASC | DESC ] [ <window_frame> ] ] )
SELECT region, amount, SUM(amount) OVER (PARTITION BY region ORDER BY amount) AS sum_over_region FROM sales;
If you came here to confirm syntax, you’re done. If you came here to get better at window functions, choose your next step.
SUM OVER is part of a bigger window-function pattern. If you want the “why”, start here: Aggregate Window Functions
Reading docs is useful. Writing the query correctly under pressure is the skill.
For the authoritative spec, use the vendor docs. This page is the fast “sanity check”.
View Snowflake Documentation →Looking for more functions across all SQL dialects? Visit the full SQL Dialects & Window Functions Documentation.