From 55810d94d03728dcad9f53d5b9e21565627aeade Mon Sep 17 00:00:00 2001 From: Andrew Brown Date: Fri, 20 Jul 2018 14:54:14 -0400 Subject: [PATCH] Refs #29563 -- Fixed SQLCompiler.execute_sql() to respect DatabaseFeatures.can_use_chunked_reads. --- django/db/models/sql/compiler.py | 5 +++-- tests/queries/test_iterator.py | 13 +++++++++++++ 2 files changed, 16 insertions(+), 2 deletions(-) diff --git a/django/db/models/sql/compiler.py b/django/db/models/sql/compiler.py index 3b91eaa35b..66ff004b6e 100644 --- a/django/db/models/sql/compiler.py +++ b/django/db/models/sql/compiler.py @@ -1089,11 +1089,12 @@ class SQLCompiler: self.col_count if self.has_extra_select else None, chunk_size, ) - if not chunked_fetch and not self.connection.features.can_use_chunked_reads: + if not chunked_fetch or not self.connection.features.can_use_chunked_reads: try: # If we are using non-chunked reads, we return the same data # structure as normally, but ensure it is all read into memory - # before going any further. Use chunked_fetch if requested. + # before going any further. Use chunked_fetch if requested, + # unless the database doesn't support it. return list(result) finally: # done with the cursor diff --git a/tests/queries/test_iterator.py b/tests/queries/test_iterator.py index 56f42c2191..7fc37b00a1 100644 --- a/tests/queries/test_iterator.py +++ b/tests/queries/test_iterator.py @@ -1,6 +1,7 @@ import datetime from unittest import mock +from django.db import connections from django.db.models.sql.compiler import cursor_iter from django.test import TestCase @@ -37,3 +38,15 @@ class QuerySetIteratorTests(TestCase): self.assertEqual(cursor_iter_mock.call_count, 1) mock_args, _mock_kwargs = cursor_iter_mock.call_args self.assertEqual(mock_args[self.itersize_index_in_mock_args], batch_size) + + def test_no_chunked_reads(self): + """ + If the database backend doesn't support chunked reads, then the + result of SQLCompiler.execute_sql() is a list. + """ + qs = Article.objects.all() + compiler = qs.query.get_compiler(using=qs.db) + features = connections[qs.db].features + with mock.patch.object(features, 'can_use_chunked_reads', False): + result = compiler.execute_sql(chunked_fetch=True) + self.assertIsInstance(result, list)