Django queryset以字典运行缓慢

Question

I am querying objects in Django and then creating a dictionary comprehension for those objects. When I do a speed test the function takes .9 seconds, even though it is only querying 104 objects. What is taking the code so long? I am running with DEBUG=False and have tried using values_list(). Also, I am using postgresql.

@speed_test
def find_user_fc_ids(user_id=1):
    try:
        flavor_compounds = UserFlavorCompound.objects.filter(user_id__in=user_id)
        return {flavor.flavor_id: flavor.score for flavor in flavor_compounds}
    except UserFlavorCompound.DoesNotExist:
        flavor_compounds = UserFlavorCompound.objects.filter(user_id__in=1)
        return {flavor.flavor_id: flavor.score for flavor in flavor_compounds}

Answer 1

Maybe you'd checkout your models. If you use ForeignKey you'd probable query them with select_related. Or if you're using ManyToMany fields you'd call them with prefetch related.

These optimizations improves your your performance quite well i guess.

You can check out: prefetch_related and select_related from official django docs.