Wrongly big numbers when use multiple of Sum, Count aggregations in annotate - django

Question

I have these models:
User:
email = EmailField()
Payment:
user = ForeignKey(User)
sum = DecimalField()
GuestAccount:
user = ForeignKey(User)
guest = ForeignKey(User)
I want to get user emails, amount of money that came from every user
and number of its guests accounts.
My query:
User.objects.annotate(
money=Sum('payment__sum'),
guests_number=Count('guestaccount')
).values('email', 'money', 'guests_number')
But money and guests_number in the result of the query are bigger then they really are:
{'guests_number': 0, 'email': 'a#b.cd', 'money': None}
{'guests_number': 20, 'email': 'user1#mail.com', 'money': Decimal('6600.00')}
{'guests_number': 4, 'email': 'user1000#test.com', 'money': Decimal('2500.00')}
{'guests_number': 0, 'email': 'zzzz#bbbbb.com', 'money': None}
I noticed that I get correct data if I split the query into 2 separate queries:
User.objects.annotate(money=Sum('payment__sum')).values('email', 'money')
User.objects.annotate(guests_number=Count('guestaccount')).values('email', 'guests_number')
Correct result of 1st half:
{'email': 'a#b.cd', 'money': None}
{'email': 'user1#mail.com', 'money': Decimal('1650.00')}
{'email': 'user1000#test.com', 'money': Decimal('1250.00')}
{'email': 'zzzz#bbbbb.com', 'money': None}
Correct result of 2nd half:
{'email': 'a#b.cd', 'guests_number': 0}
{'email': 'user1#mail.com', 'guests_number': 4}
{'email': 'user1000#test.com', 'guests_number': 2}
{'email': 'zzzz#bbbbb.com', 'guests_number': 0}
Also I noticed that I can add distinct=True in Count aggregation:
User.objects.annotate(
money=Sum('payment__sum'),
guests_number=Count('guestaccount', distinct=True)
).values('email', 'money', 'guests_number')
It fixes guests_number:
{'guests_number': 0, 'email': 'a#b.cd', 'money': None}
{'guests_number': 4, 'email': 'user1#mail.com', 'money': Decimal('6600.00')}
{'guests_number': 2, 'email': 'user1000#test.com', 'money': Decimal('2500.00')}
{'guests_number': 0, 'email': 'zzzz#bbbbb.com', 'money': None}
Unfortunatly, there are no distinct parameter in Sum aggregation.
What is wrong with my query? How to fix these numbers getting bigger with every aggregation in annotate?

Answer 1

Raw SQL query investigation showed that the problem comes from multiple LEFT OUTER JOINs. So I ended up with raw SQL:
User.objects.extra(select={
"money": """
SELECT SUM("website_payment"."sum")
FROM "website_payment"
WHERE "website_user"."id" = "website_payment"."user_id"
""",
"guests_number": """
SELECT COUNT("guests_guestaccount"."id")
FROM "guests_guestaccount"
WHERE "website_user"."id" = "guests_guestaccount"."user_id"
""",
}
).values('email', 'money', 'guests_number')
But I need to annotate these fields into queried objects and extra don't do it.