windowing_error window function … requires an OVER clause — 42P20

Symptoms

A window function was called without the required OVER clause. Window functions must specify a window, so PostgreSQL raises SQLSTATE 42P20 (windowing_error).

• A function like rank() or row_number() used without OVER.
• These functions are not aggregates and need a window definition.
• Common when confusing window functions with aggregates.

What the server log shows

ERROR:  window function rank requires an OVER clause

Why PostgreSQL raises this — what the manual says

Section 3.5 Window Functions:

“A window function call always contains an OVER clause directly following the window function’s name and argument(s).”

Window functions operate over a set of rows defined by OVER (partitioning/ordering). Without it, the function has no window to compute over, so PostgreSQL rejects the call with 42P20.

Common causes

• Calling a window-only function without OVER.
• Treating row_number()/rank() like a scalar function.
• Forgetting the window definition.

How to fix it

1. Add an OVER clause: rank() OVER (ORDER BY score DESC).
2. Use OVER () for a single full-result window if appropriate.
3. If you meant an aggregate, use the aggregate function with GROUP BY instead.

Related & next steps

• SQLSTATE 42P20 — Windowing Error (full reference)
• Message: window does not exist
• Glossary: Window function

Reference: PostgreSQL 18 Section 3.5 “Window Functions”.