I have a model with a FK on User table:
from django.contrib.auth.models import User
class Ticket(models.Model):
assigned_to = models.ForeignKey(User, null=True, blank=True)
...
Then I have these two querysets:
>>> q1 = Ticket.objects.filter(assigned_to__isnull=True)
>>> q2 = Ticket.objects.exclude(assigned_to__isnull=False)
I thought they shoud generate the same SQL query as they are
conceptually the same thing.
But if I print their query I got:
>>> print q1.query
SELECT ...
FROM "ticket_ticket"
LEFT OUTER JOIN "auth_user" ON ("ticket_ticket"."assigned_id" =
"auth_user"."id")
WHERE "auth_user"."id" IS NULL
>>> print q2.query
SELECT ...
FROM "ticket_ticket"
WHERE NOT ("ticket_ticket"."assigned_id" IS NOT NULL)
The exclude version is much more efficient.
Is this by design?
Ciao.
Marco.
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