[AAP-93974] perf(api): optimize non-superuser job list pagination (#16668)

perf(api): optimize non-superuser job list pagination

Co-authored-by: Jake Jackson <24478650+thedoubl3j@users.noreply.github.com>

awx/api/pagination.py

@@ -45,6 +45,15 @@ class UnifiedJobPaginator(DjangoPaginator):
         return UnifiedJob.objects.count()
 
 
+class JobPaginator(DjangoPaginator):
+    """Count visible jobs through a primary-key subquery instead of full rows."""
+
+    @cached_property
+    def count(self):
+        visible_pks = self.object_list.order_by().values("pk")
+        return self.object_list.model.objects.filter(pk__in=visible_pks).count()
+
+
 class Pagination(pagination.PageNumberPagination):
     page_size_query_param = "page_size"
     max_page_size = settings.MAX_PAGE_SIZE
@@ -135,6 +144,10 @@ class UnifiedJobPagination(Pagination):
         return DjangoPaginator
 
 
+class JobPagination(Pagination):
+    django_paginator_class = JobPaginator
+
+
 class LimitPagination(pagination.BasePagination):
     default_limit = api_settings.PAGE_SIZE
     limit_query_param = "limit"

awx/api/views/__init__.py

@@ -130,7 +130,7 @@ from awx.api.views.mixin import (
     NoTruncateMixin,
     UnifiedJobExcludeMixin,
 )
-from awx.api.pagination import ActivityStreamPagination, UnifiedJobEventPagination, UnifiedJobPagination
+from awx.api.pagination import ActivityStreamPagination, JobPagination, UnifiedJobEventPagination, UnifiedJobPagination
 from awx.main.utils import set_environ
 
 logger = logging.getLogger('awx.api.views')
@@ -3885,6 +3885,7 @@ class SystemJobTemplateNotificationTemplatesSuccessList(SystemJobTemplateNotific
 class JobList(UnifiedJobExcludeMixin, ListAPIView):
     model = models.Job
     serializer_class = serializers.JobListSerializer
+    pagination_class = JobPagination
     resource_purpose = 'jobs'
 
     @extend_schema_if_available(extensions={"x-ai-description": "A list of jobs."})