Fixed #30511 -- Used identity columns instead of serials on PostgreSQL.

tests/backends/postgresql/test_introspection.py

@@ -27,3 +27,18 @@ class DatabaseSequenceTests(TestCase):
                 seqs,
                 [{"table": Person._meta.db_table, "column": "id", "name": "pers_seq"}],
             )
+
+    def test_get_sequences_old_serial(self):
+        with connection.cursor() as cursor:
+            cursor.execute("CREATE TABLE testing (serial_field SERIAL);")
+            seqs = connection.introspection.get_sequences(cursor, "testing")
+            self.assertEqual(
+                seqs,
+                [
+                    {
+                        "table": "testing",
+                        "column": "serial_field",
+                        "name": "testing_serial_field_seq",
+                    }
+                ],
+            )