Fix query

src/pretix/base/services/checkin.py

@@ -1045,7 +1045,7 @@ def perform_checkin(op: OrderPosition, clist: CheckinList, given_answers: dict,
 
     with transaction.atomic():
         # Lock order positions, if it is an entry. We don't need it for exits, as a race condition wouldn't be problematic
-        opqs = OrderPosition.all
+        opqs = OrderPosition.all.select_related("order", "item")
         if type != Checkin.TYPE_EXIT:
             opqs = opqs.select_for_update(of=OF_SELF)
         op = opqs.get(pk=op.pk)

src/tests/base/test_checkin.py

@@ -1186,7 +1186,7 @@ def test_rules_reasoning_prefer_number_over_date(event, position, clist):
 
 @pytest.mark.django_db(transaction=True)
 def test_position_queries(django_assert_max_num_queries, position, clist):
-    with django_assert_max_num_queries(13) as captured:
+    with django_assert_max_num_queries(12) as captured:
         perform_checkin(position, clist, {})
     if 'sqlite' not in settings.DATABASES['default']['ENGINE']:
         assert any('FOR UPDATE' in s['sql'] for s in captured)