[1.8.x] Reverted "Fixed #6785 -- Made QuerySet.get() fetch a limited number of rows."

This reverts commit da79ccca1d.

This optimized the unsuccessful case at the expense of the successful one.

Backport of 293fd5da5b from master

django/db/models/query.py

@@ -23,10 +23,6 @@ from django.utils import six
 from django.utils import timezone
 from django.utils.version import get_version
 
-# The maximum number (one less than the max to be precise) of results to fetch
-# in a get() query
-MAX_GET_RESULTS = 20
-
 # The maximum number of items to display in a QuerySet.__repr__
 REPR_OUTPUT_SIZE = 20
 
@@ -326,21 +322,17 @@ class QuerySet(object):
         clone = self.filter(*args, **kwargs)
         if self.query.can_filter():
             clone = clone.order_by()
-        if (not clone.query.select_for_update or
-                connections[self.db].features.supports_select_for_update_with_limit):
-            clone = clone[:MAX_GET_RESULTS + 1]
         num = len(clone)
         if num == 1:
             return clone._result_cache[0]
         if not num:
             raise self.model.DoesNotExist(
                 "%s matching query does not exist." %
-                self.model._meta.object_name)
-        raise self.model.MultipleObjectsReturned(
-            "get() returned more than one %s -- it returned %s!" % (
-                self.model._meta.object_name,
-                num if num <= MAX_GET_RESULTS else 'more than %s' % MAX_GET_RESULTS
+                self.model._meta.object_name
             )
+        raise self.model.MultipleObjectsReturned(
+            "get() returned more than one %s -- it returned %s!" %
+            (self.model._meta.object_name, num)
         )
 
     def create(self, **kwargs):

tests/basic/tests.py

@@ -10,7 +10,7 @@ from django.db import DatabaseError
 from django.db.models.fields import Field
 from django.db.models.fields.related import ForeignObjectRel
 from django.db.models.manager import BaseManager
-from django.db.models.query import QuerySet, EmptyQuerySet, ValuesListQuerySet, MAX_GET_RESULTS
+from django.db.models.query import QuerySet, EmptyQuerySet, ValuesListQuerySet
 from django.test import TestCase, TransactionTestCase, skipIfDBFeature, skipUnlessDBFeature
 from django.utils import six
 from django.utils.translation import ugettext_lazy
@@ -178,30 +178,6 @@ class ModelTest(TestCase):
 
         self.assertNotEqual(Article.objects.get(id__exact=a1.id), Article.objects.get(id__exact=a2.id))
 
-    def test_multiple_objects_max_num_fetched(self):
-        """
-        #6785 - get() should fetch a limited number of results.
-        """
-        Article.objects.bulk_create(
-            Article(headline='Area %s' % i, pub_date=datetime(2005, 7, 28))
-            for i in range(MAX_GET_RESULTS)
-        )
-        six.assertRaisesRegex(
-            self,
-            MultipleObjectsReturned,
-            "get\(\) returned more than one Article -- it returned %d!" % MAX_GET_RESULTS,
-            Article.objects.get,
-            headline__startswith='Area',
-        )
-        Article.objects.create(headline='Area %s' % MAX_GET_RESULTS, pub_date=datetime(2005, 7, 28))
-        six.assertRaisesRegex(
-            self,
-            MultipleObjectsReturned,
-            "get\(\) returned more than one Article -- it returned more than %d!" % MAX_GET_RESULTS,
-            Article.objects.get,
-            headline__startswith='Area',
-        )
-
     @skipUnlessDBFeature('supports_microsecond_precision')
     def test_microsecond_precision(self):
         # In PostgreSQL, microsecond-level precision is available.