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django/tests/queries/test_explain.py

103 lines
5.0 KiB
Python

import unittest
from django.db import NotSupportedError, connection, transaction
from django.db.models import Count
from django.test import TestCase, skipIfDBFeature, skipUnlessDBFeature
from django.test.utils import CaptureQueriesContext
from .models import Tag
@skipUnlessDBFeature('supports_explaining_query_execution')
class ExplainTests(TestCase):
def test_basic(self):
querysets = [
Tag.objects.filter(name='test'),
Tag.objects.filter(name='test').select_related('parent'),
Tag.objects.filter(name='test').prefetch_related('children'),
Tag.objects.filter(name='test').annotate(Count('children')),
Tag.objects.filter(name='test').values_list('name'),
Tag.objects.order_by().union(Tag.objects.order_by().filter(name='test')),
Tag.objects.all().select_for_update().filter(name='test'),
]
supported_formats = connection.features.supported_explain_formats
all_formats = (None,) + tuple(supported_formats) + tuple(f.lower() for f in supported_formats)
for idx, queryset in enumerate(querysets):
for format in all_formats:
with self.subTest(format=format, queryset=idx):
if connection.vendor == 'mysql':
# This does a query and caches the result.
connection.features.needs_explain_extended
with self.assertNumQueries(1), CaptureQueriesContext(connection) as captured_queries:
result = queryset.explain(format=format)
self.assertTrue(captured_queries[0]['sql'].startswith(connection.ops.explain_prefix))
self.assertIsInstance(result, str)
self.assertTrue(result)
@skipUnlessDBFeature('validates_explain_options')
def test_unknown_options(self):
with self.assertRaisesMessage(ValueError, 'Unknown options: test, test2'):
Tag.objects.all().explain(test=1, test2=1)
def test_unknown_format(self):
msg = 'DOES NOT EXIST is not a recognized format.'
if connection.features.supported_explain_formats:
msg += ' Allowed formats: %s' % ', '.join(sorted(connection.features.supported_explain_formats))
with self.assertRaisesMessage(ValueError, msg):
Tag.objects.all().explain(format='does not exist')
@unittest.skipUnless(connection.vendor == 'postgresql', 'PostgreSQL specific')
def test_postgres_options(self):
qs = Tag.objects.filter(name='test')
test_options = [
{'COSTS': False, 'BUFFERS': True, 'ANALYZE': True},
{'costs': False, 'buffers': True, 'analyze': True},
{'verbose': True, 'timing': True, 'analyze': True},
{'verbose': False, 'timing': False, 'analyze': True},
]
if connection.pg_version >= 100000:
test_options.append({'summary': True})
for options in test_options:
with self.subTest(**options), transaction.atomic():
with CaptureQueriesContext(connection) as captured_queries:
qs.explain(format='text', **options)
self.assertEqual(len(captured_queries), 1)
for name, value in options.items():
option = '{} {}'.format(name.upper(), 'true' if value else 'false')
self.assertIn(option, captured_queries[0]['sql'])
@unittest.skipUnless(connection.vendor == 'mysql', 'MySQL specific')
def test_mysql_text_to_traditional(self):
# Initialize the cached property, if needed, to prevent a query for
# the MySQL version during the QuerySet evaluation.
connection.features.needs_explain_extended
with CaptureQueriesContext(connection) as captured_queries:
Tag.objects.filter(name='test').explain(format='text')
self.assertEqual(len(captured_queries), 1)
self.assertIn('FORMAT=TRADITIONAL', captured_queries[0]['sql'])
@unittest.skipUnless(connection.vendor == 'mysql', 'MySQL < 5.7 specific')
def test_mysql_extended(self):
# Inner skip to avoid module level query for MySQL version.
if not connection.features.needs_explain_extended:
raise unittest.SkipTest('MySQL < 5.7 specific')
qs = Tag.objects.filter(name='test')
with CaptureQueriesContext(connection) as captured_queries:
qs.explain(format='json')
self.assertEqual(len(captured_queries), 1)
self.assertNotIn('EXTENDED', captured_queries[0]['sql'])
with CaptureQueriesContext(connection) as captured_queries:
qs.explain(format='text')
self.assertEqual(len(captured_queries), 1)
self.assertNotIn('EXTENDED', captured_queries[0]['sql'])
@skipIfDBFeature('supports_explaining_query_execution')
class ExplainUnsupportedTests(TestCase):
def test_message(self):
msg = 'This backend does not support explaining query execution.'
with self.assertRaisesMessage(NotSupportedError, msg):
Tag.objects.filter(name='test').explain()