⚡ [#538] Optimize objects list performance

the filter to only include the objectrecords with the highest index per object was causing major performance degradations, especially in combination with filters on data_attrs.
    Instead of using `Max(...)` together with GROUP BY, we now use Window to figure out the max index per object which is more efficient for larger datasets

src/objects/core/query.py

@@ -1,4 +1,6 @@
 from django.db import models
+from django.db.models import F, Window
+from django.db.models.functions import RowNumber
 
 from vng_api_common.utils import get_uuid_from_path
 from zgw_consumers.models import Service
@@ -43,14 +45,20 @@ def keep_max_record_per_object(self):
         """
         Return records with the largest index for the object
         """
-        filtered_records = self.order_by()
-        grouped_records = (
-            filtered_records.filter(object=models.OuterRef("object"))
-            .values("object")
-            .annotate(max_index=models.Max("index"))
-            .values("max_index")
+        filtered_records = (
+            self.filter(object=models.OuterRef("object"))
+            .annotate(
+                row_number=Window(
+                    expression=RowNumber(),
+                    partition_by=[F("object")],
+                    order_by=F("index").desc(),
+                )
+            )
+            .filter(row_number=1)
+            .values("index")
         )
-        return self.filter(index=models.Subquery(grouped_records))
+
+        return self.filter(index__in=filtered_records)
 
     def filter_for_date(self, date):
         """

src/objects/tests/v2/test_object_api.py

@@ -594,6 +594,44 @@ def test_list_available_today(self):
             self.assertEqual(object_data["uuid"], str(self.object.uuid))
             self.assertEqual(object_data["record"]["data"], {"name": "new"})
 
+    @freeze_time("2024-08-31")
+    def test_only_show_latest_index(self):
+        """
+        In the list endpoint, only the latest record that existed at the given date
+        should show up
+        """
+        object_url = reverse("object-detail", kwargs={"uuid": self.object.uuid})
+        object2 = ObjectFactory.create(object_type=self.object_type)
+        object2_url = reverse("object-detail", kwargs={"uuid": object2.uuid})
+        ObjectRecordFactory.create(
+            object=object2,
+            index=1,
+            data={"name": "old"},
+            start_at="2024-08-01",
+            end_at="2024-08-28",
+            registration_at="2024-08-02",
+        )
+        ObjectRecordFactory.create(
+            object=object2,
+            index=2,
+            data={"name": "new"},
+            start_at="2024-08-28",
+            end_at="2024-09-30",
+            registration_at="2024-08-02",
+        )
+
+        response = self.client.get(self.url, {"date": "2024-08-30"})
+
+        self.assertEqual(response.status_code, status.HTTP_200_OK)
+
+        data = response.json()
+
+        self.assertEqual(data["count"], 2)
+        self.assertEqual(data["results"][0]["record"]["index"], 2)
+        self.assertEqual(data["results"][0]["url"], f"http://testserver{object2_url}")
+        self.assertEqual(data["results"][1]["record"]["index"], 1)
+        self.assertEqual(data["results"][1]["url"], f"http://testserver{object_url}")
+
     def test_list_available_for_date(self):
         with self.subTest("filter on old name"):
             response = self.client.get(