old_contents: from django.db.models import Q
  from django.utils import timezone
  
  
  def remove_expired_record(expire_days, query_set, time_attr_name="timestamp"):
      expired_record_filter = {"%s__lt" % time_attr_name: timezone.now() - timezone.timedelta(days=expire_days)}
      q = Q(**expired_record_filter)
      final_q = query_set.filter(q)
      # cnt = 0
      # for i in final_q:
      #     i.delete()
      #     cnt += 1
      #     if cnt % 1000 == 0:
      #         print "%d deleted" % cnt
      final_q.delete()
  
new_contents: from django.db.models import Q
  from django.utils import timezone
  
  
  def remove_expired_record(expire_days, query_set, time_attr_name="timestamp"):
      expired_record_filter = {"%s__lt" % time_attr_name: timezone.now() - timezone.timedelta(days=expire_days)}
      q = Q(**expired_record_filter)
      final_q = query_set.filter(q)
      if final_q.count() > 1000:
          final_q = final_q[:999]
      # cnt = 0
      # for i in final_q:
      #     i.delete()
      #     cnt += 1
      #     if cnt % 1000 == 0:
      #         print "%d deleted" % cnt
      final_q.delete()
  
subject: Delete item with limited size.