What happens when some fields fetched using .only() in a queryset but more fields fetched later ?

[acpmasquerade]

When .only("field1", "field2") filter is applied, only the mentioned fields are fetched in the database query.

For example, for a model User
qs = User.objects.only("name", "email")

is translated to SQL similar to
select id, name, email from user

However,
If field3 is fetched later on, a separate query is executed to suffice the invocation.

Therefore, if required to run a field inside a loop, each iteration will create a new database query.

qs = User.objects.only("name")
for user in qsp[0:10]:
  print(user.email)

• The above code makes 1 + 10 database queries