This page is a quick reference checkpoint for MAX OVER in Postgres: behavior, syntax rules, edge cases, and a minimal example; plus the official vendor documentation.
MAX OVER returns the largest value in the window frame.
When an aggregate function (like MAX) is used as a window function, it aggregates over the rows within the current row's window frame; the default frame when ORDER BY is present is from start of partition to current row (and peers).
If this behavior feels unintuitive, the tutorial below explains the underlying pattern step-by-step.
Any built-in or user-defined ordinary aggregate (such as MAX) can be used as a window function with an OVER clause.
SELECT MAX(salary) OVER (PARTITION BY department ORDER BY salary) FROM empsalary;
If you came here to confirm syntax, you’re done. If you came here to get better at window functions, choose your next step.
MAX 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 Postgres Documentation →Looking for more functions across all SQL dialects? Visit the full SQL Dialects & Window Functions Documentation.