Fixed #26608 -- Added support for window expressions (OVER clause).

Thanks Josh Smeaton, Mariusz Felisiak, Sergey Fedoseev, Simon Charettes,
Adam Chainz/Johnson and Tim Graham for comments and reviews and Jamie
Cockburn for initial patch.

1 files changed, 10 insertions, 0 deletions

diff --git a/django/db/backends/postgresql/operations.py b/django/db/backends/postgresql/operations.py
index bff8e87d68..268fa99b51 100644
--- a/django/db/backends/postgresql/operations.py
+++ b/django/db/backends/postgresql/operations.py
@@ -1,6 +1,7 @@
 from psycopg2.extras import Inet
 
 from django.conf import settings
+from django.db import NotSupportedError
 from django.db.backends.base.operations import BaseDatabaseOperations
 
 
@@ -247,3 +248,12 @@ class DatabaseOperations(BaseDatabaseOperations):
             rhs_sql, rhs_params = rhs
             return "(interval '1 day' * (%s - %s))" % (lhs_sql, rhs_sql), lhs_params + rhs_params
         return super().subtract_temporals(internal_type, lhs, rhs)
+
+    def window_frame_range_start_end(self, start=None, end=None):
+        start_, end_ = super().window_frame_range_start_end(start, end)
+        if (start and start < 0) or (end and end > 0):
+            raise NotSupportedError(
+                'PostgreSQL only supports UNBOUNDED together with PRECEDING '
+                'and FOLLOWING.'
+            )
+        return start_, end_