usage of iterator() on django queryset

Question

I came across some strange behaviour recently, and need to check my understanding.

I\'m using a simple filter in the model and then iterating over the results.

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Answer 1

A QuerySet typically caches its results internally so that repeated evaluations do not result in additional queries. In contrast, iterator() will read results directly, without doing any caching at the QuerySet level.

https://docs.djangoproject.com/en/dev/ref/models/querysets/

Answer 2

oddly, it was returning only a partial list of books.

That's not how the queryset must work. Iterating over queryset should give you every record returned by your database. Debug your code. You'll find the error, otherwise debug it again.

It's easy to check in the REPL. Run manage.py shell:

from app.models import Model
for o in Model.objects.filter(fieldname="foo"): print o

#Let's see DB query
from django.db import connection
print(connection.queries)