Fix(oracle): improve handling of KEEP (...) OVER (...) window syntax (#…

…1953)

sqlglot/parser.py

@@ -4172,7 +4172,7 @@ def _parse_window(
 
         self._match_r_paren()
 
-        return self.expression(
+        window = self.expression(
             exp.Window,
             this=this,
             partition_by=partition,
@@ -4183,6 +4183,12 @@ def _parse_window(
             first=first,
         )
 
+        # This covers Oracle's FIRST/LAST syntax: aggregate KEEP (...) OVER (...)
+        if self._match_set(self.WINDOW_BEFORE_PAREN_TOKENS, advance=False):
+            return self._parse_window(window, alias=alias)
+
+        return window
+
     def _parse_window_spec(self) -> t.Dict[str, t.Optional[str | exp.Expression]]:
         self._match(TokenType.BETWEEN)
 

tests/dialects/test_oracle.py

@@ -23,6 +23,11 @@ def test_oracle(self):
         self.validate_identity(
             "SELECT MIN(column_name) KEEP (DENSE_RANK FIRST ORDER BY column_name DESC) FROM table_name"
         )
+        self.validate_identity(
+            "SELECT last_name, department_id, salary, MIN(salary) KEEP (DENSE_RANK FIRST ORDER BY commission_pct) "
+            'OVER (PARTITION BY department_id) AS "Worst", MAX(salary) KEEP (DENSE_RANK LAST ORDER BY commission_pct) '
+            'OVER (PARTITION BY department_id) AS "Best" FROM employees ORDER BY department_id, salary, last_name'
+        )
 
         self.validate_all(
             "NVL(NULL, 1)",