Fixed #29568 -- Prevented unnecessary UPDATE queries creating child models.

tests/model_inheritance/tests.py

@@ -133,6 +133,24 @@ class ModelInheritanceTests(TestCase):
             if 'UPDATE' in sql:
                 self.assertEqual(expected_sql, sql)
 
+    def test_create_child_no_update(self):
+        """Creating a child with non-abstract parents only issues INSERTs."""
+        def a():
+            GrandChild.objects.create(
+                email='grand_parent@example.com',
+                first_name='grand',
+                last_name='parent',
+            )
+
+        def b():
+            GrandChild().save()
+        for i, test in enumerate([a, b]):
+            with self.subTest(i=i), self.assertNumQueries(4), CaptureQueriesContext(connection) as queries:
+                test()
+                for query in queries:
+                    sql = query['sql']
+                    self.assertIn('INSERT INTO', sql, sql)
+
     def test_eq(self):
         # Equality doesn't transfer in multitable inheritance.
         self.assertNotEqual(Place(id=1), Restaurant(id=1))