perf: optimize DB queries

cohort/views/cohort_result.py

@@ -55,7 +55,9 @@ class Meta:
 
 
 class CohortResultViewSet(NestedViewSetMixin, UserObjectsRestrictedViewSet):
-    queryset = CohortResult.objects.select_related('request_query_snapshot__request')
+    queryset = CohortResult.objects.select_related('dated_measure',
+                                                   'dated_measure_global',
+                                                   'request_query_snapshot__request')
     serializer_class = CohortResultSerializer
     http_method_names = ['get', 'post', 'patch', 'delete']
     swagger_tags = ["Cohorts"]

cohort/views/request.py

@@ -1,10 +1,11 @@
+from django.db.models.query import Prefetch
 from django.http import QueryDict
 from drf_spectacular.utils import extend_schema_view, extend_schema
 from rest_framework import status
 from rest_framework_extensions.mixins import NestedViewSetMixin
 
 from admin_cohort.tools.cache import cache_response
-from cohort.models import Request
+from cohort.models import Request, RequestQuerySnapshot as RQS
 from cohort.serializers import RequestSerializer, RequestCreateSerializer, RequestPatchSerializer
 from cohort.views.shared import UserObjectsRestrictedViewSet
 
@@ -19,7 +20,8 @@
     destroy=extend_schema(responses={status.HTTP_204_NO_CONTENT: None})
 )
 class RequestViewSet(NestedViewSetMixin, UserObjectsRestrictedViewSet):
-    queryset = Request.objects.all()
+    queryset = Request.objects.prefetch_related(Prefetch(lookup='query_snapshots',
+                                                         queryset=RQS.objects.prefetch_related('cohort_results')))
     serializer_class = RequestSerializer
     http_method_names = ["get", "post", "patch", "delete"]
     filterset_fields = ('favorite',