Ticket #2565: 2565.diff

docs/tutorial04.txt

@@ -206 +206 @@
 ``template_name='polls/results.html'``. Otherwise, both views would use the same
 template. Note that we use ``dict()`` to return an altered dictionary in place.
 
+.. admonition:: ``all()`` is lazy
+
+    It might look a little frightening to see ``Poll.objects.all()``
+    being used in a detail view which only needs one ``Poll`` object,
+    but don't worry; ``Poll.objects.all()`` is actually a special
+    object called a ``QuerySet``, which is "lazy" and doesn't hit your
+    database until it absolutely has to. By the time the database
+    query happens, the ``object_detail`` generic view will have
+    narrowed its scope down to a single object, so the eventual query
+    will only select one row from the database. If you'd like to know
+    more about how that works, The Django database API documentation
+    explains `the lazy nature of ``QuerySet`` objects`_.
+
+.. _the lazy nature of ``QuerySet`` objects: ../db_api/#querysets-are-lazy
+
 In previous parts of the tutorial, the templates have been provided with a context
 that contains the ``poll`` and ``latest_poll_list`` context variables. However,
 the generic views provide the variables ``object`` and ``object_list`` as context.