[Django]-Django lazy QuerySet and pagination

If you want to see where are occurring, import django.db.connection and inspect queries

>>> from django.db import connection
>>> from django.core.paginator import Paginator
>>> queryset = Entry.objects.all()

Lets create the paginator, and see if any queries occur:

>>> paginator = Paginator(queryset, 10)
>>> print connection.queries 
[]

None yet.

>>> page = paginator.page(4)
>>> page
<Page 4 of 788>
>>> print connection.queries 
[{'time': '0.014', 'sql': 'SELECT COUNT(*) FROM `entry`'}]

Creating the page has produced one query, to count how many entries are in the queryset. The entries have not been fetched yet.

Assign the page’s objects to the variable ‘objects’:

>>> objects = page.object_list
>>> print connection.queries
[{'time': '0.014', 'sql': 'SELECT COUNT(*) FROM `entry`'}]

This still hasn’t caused the entries to be fetched.

Generate the HttpResponse from the object list

>>> response = HttpResponse(page.object_list)
>>> print connection.queries
[{'time': '0.014', 'sql': 'SELECT COUNT(*) FROM `entry`'}, {'time': '0.011', 'sql': 'SELECT `entry`.`id`, <snip> FROM `entry` LIMIT 10 OFFSET 30'}]

Finally, the entries have been fetched.