[1.11.x] Fixed #28817 -- Made QuerySet.iterator() use server-side cursors after values() and values_list().

Backport of d97f026a7ab5212192426e45121f7a52751a2044 from master

django/db/models/query.py

@@ -103,7 +103,7 @@ class ValuesIterable(BaseIterable):
         # extra(select=...) cols are always at the start of the row.
         names = extra_names + field_names + annotation_names
 
-        for row in compiler.results_iter():
+        for row in compiler.results_iter(chunked_fetch=self.chunked_fetch):
             yield dict(zip(names, row))
 
 
@@ -119,7 +119,7 @@ class ValuesListIterable(BaseIterable):
         compiler = query.get_compiler(queryset.db)
 
         if not query.extra_select and not query.annotation_select:
-            for row in compiler.results_iter():
+            for row in compiler.results_iter(chunked_fetch=self.chunked_fetch):
                 yield tuple(row)
         else:
             field_names = list(query.values_select)
@@ -135,7 +135,7 @@ class ValuesListIterable(BaseIterable):
             else:
                 fields = names
 
-            for row in compiler.results_iter():
+            for row in compiler.results_iter(chunked_fetch=self.chunked_fetch):
                 data = dict(zip(names, row))
                 yield tuple(data[f] for f in fields)
 
@@ -149,7 +149,7 @@ class FlatValuesListIterable(BaseIterable):
     def __iter__(self):
         queryset = self.queryset
         compiler = queryset.query.get_compiler(queryset.db)
-        for row in compiler.results_iter():
+        for row in compiler.results_iter(chunked_fetch=self.chunked_fetch):
             yield row[0]
 
 

django/db/models/sql/compiler.py

@@ -833,12 +833,12 @@ class SQLCompiler(object):
             row[pos] = value
         return tuple(row)
 
-    def results_iter(self, results=None):
+    def results_iter(self, results=None, chunked_fetch=False):
         """
         Returns an iterator over the results from executing this query.
         """
         if results is None:
-            results = self.execute_sql(MULTI)
+            results = self.execute_sql(MULTI, chunked_fetch=chunked_fetch)
         fields = [s[0] for s in self.select[0:self.col_count]]
         converters = self.get_converters(fields)
         for rows in results:

docs/releases/1.11.8.txt

@@ -18,3 +18,6 @@ Bugfixes
 
 * Fixed incorrect index name truncation when using a namespaced ``db_table``
   (:ticket:`28792`).
+
+* Made ``QuerySet.iterator()`` use server-side cursors on PostgreSQL after
+  ``values()`` and ``values_list()`` (:ticket:`28817`).

tests/backends/test_postgresql.py

@@ -3,7 +3,7 @@ import unittest
 from collections import namedtuple
 from contextlib import contextmanager
 
-from django.db import connection
+from django.db import connection, models
 from django.test import TestCase
 
 from .models import Person
@@ -53,6 +53,19 @@ class ServerSideCursorsPostgres(TestCase):
     def test_server_side_cursor(self):
         self.assertUsesCursor(Person.objects.iterator())
 
+    def test_values(self):
+        self.assertUsesCursor(Person.objects.values('first_name').iterator())
+
+    def test_values_list(self):
+        self.assertUsesCursor(Person.objects.values_list('first_name').iterator())
+
+    def test_values_list_flat(self):
+        self.assertUsesCursor(Person.objects.values_list('first_name', flat=True).iterator())
+
+    def test_values_list_fields_not_equal_to_names(self):
+        expr = models.Count('id')
+        self.assertUsesCursor(Person.objects.annotate(id__count1=expr).values_list(expr, 'id__count1').iterator())
+
     def test_server_side_cursor_many_cursors(self):
         persons = Person.objects.iterator()
         persons2 = Person.objects.iterator()