Avoid unneccesary logs in some highly-used API endpoints

src/pretix/api/views/event.py

@@ -244,6 +244,11 @@ class SubEventViewSet(ConditionalListView, viewsets.ModelViewSet):
         )
 
     def perform_update(self, serializer):
+        if serializer.data == self.get_serializer(instance=serializer.instance).data:
+            # Performance optimization: If nothing was changed, we do not need to save or log anything.
+            # This costs us a few cycles on save, but avoids thousands of lines in our log.
+            return
+
         super().perform_update(serializer)
 
         serializer.instance.log_action(

src/pretix/api/views/item.py

@@ -65,6 +65,10 @@ class ItemViewSet(ConditionalListView, viewsets.ModelViewSet):
         return ctx
 
     def perform_update(self, serializer):
+        if serializer.data == self.get_serializer(instance=serializer.instance).data:
+            # Performance optimization: If nothing was changed, we do not need to save or log anything.
+            # This costs us a few cycles on save, but avoids thousands of lines in our log.
+            return
         serializer.save(event=self.request.event)
         serializer.instance.log_action(
             'pretix.event.item.changed',
@@ -452,6 +456,11 @@ class QuotaViewSet(ConditionalListView, viewsets.ModelViewSet):
         return ctx
 
     def perform_update(self, serializer):
+        if serializer.data == self.get_serializer(instance=serializer.instance).data:
+            # Performance optimization: If nothing was changed, we do not need to save or log anything.
+            # This costs us a few cycles on save, but avoids thousands of lines in our log.
+            return
+
         current_subevent = serializer.instance.subevent
         serializer.save(event=self.request.event)
         request_subevent = serializer.instance.subevent

src/tests/api/test_items.py

@@ -1553,6 +1553,22 @@ def test_quota_update(token_client, organizer, event, quota, item):
     quota = Quota.objects.get(pk=resp.data['id'])
     assert quota.name == "Ticket Quota Update"
     assert quota.size == 111
+    assert quota.all_logentries().count() == 1
+
+
+@pytest.mark.django_db
+def test_quota_update_unchanged(token_client, organizer, event, quota, item):
+    resp = token_client.patch(
+        '/api/v1/organizers/{}/events/{}/quotas/{}/'.format(organizer.slug, event.slug, quota.pk),
+        {
+            "size": 200,
+        },
+        format='json'
+    )
+    assert resp.status_code == 200
+    quota = Quota.objects.get(pk=resp.data['id'])
+    assert quota.size == 200
+    assert quota.all_logentries().count() == 0
 
 
 @pytest.mark.django_db