Fixed #25470 -- Avoided unnecessary, expensive DATETIME typecast on MySQL. (0f6d51e6) · Commits · Dom Sekotill / django

django/db/backends/mysql/operations.py

+8 −10

Original line number	Diff line number	Diff line
		@@ -27,17 +27,15 @@ class DatabaseOperations(BaseDatabaseOperations):
		return "EXTRACT(%s FROM %s)" % (lookup_type.upper(), field_name)

		def date_trunc_sql(self, lookup_type, field_name):
		fields = ['year', 'month', 'day', 'hour', 'minute', 'second']
		format = ('%%Y-', '%%m', '-%%d', ' %%H:', '%%i', ':%%s') # Use double percents to escape.
		format_def = ('0000-', '01', '-01', ' 00:', '00', ':00')
		try:
		i = fields.index(lookup_type) + 1
		except ValueError:
		sql = field_name
		fields = {
		'year': '%%Y-01-01',
		'month': '%%Y-%%m-01',
		} # Use double percents to escape.
		if lookup_type in fields:
		format_str = fields[lookup_type]
		return "CAST(DATE_FORMAT(%s, '%s') AS DATE)" % (field_name, format_str)
		else:
		format_str = ''.join([f for f in format[:i]] + [f for f in format_def[i:]])
		sql = "CAST(DATE_FORMAT(%s, '%s') AS DATETIME)" % (field_name, format_str)
		return sql
		return "DATE(%s)" % (field_name)

		def _convert_field_to_tz(self, field_name, tzname):
		if settings.USE_TZ:

tests/dates/models.py

+2 −0

Original line number	Diff line number	Diff line
		from __future__ import unicode_literals

		from django.db import models
		from django.utils import timezone
		from django.utils.encoding import python_2_unicode_compatible


		@@ -8,6 +9,7 @@ from django.utils.encoding import python_2_unicode_compatible
		class Article(models.Model):
		title = models.CharField(max_length=100)
		pub_date = models.DateField()
		pub_datetime = models.DateTimeField(default=timezone.now())

		categories = models.ManyToManyField("Category", related_name="articles")

tests/dates/tests.py

+32 −2

Original line number	Diff line number	Diff line
		from __future__ import unicode_literals

		import datetime
		from unittest import skipUnless

		from django.core.exceptions import FieldError
		from django.test import TestCase
		from django.db import connection
		from django.test import TestCase, override_settings
		from django.utils import six

		from .models import Article, Category, Comment
		@@ -95,7 +97,7 @@ class DatesTests(TestCase):
		self,
		FieldError,
		"Cannot resolve keyword u?'invalid_field' into field. Choices are: "
		"categories, comments, id, pub_date, title",
		"categories, comments, id, pub_date, pub_datetime, title",
		Article.objects.dates,
		"invalid_field",
		"year",
		@@ -121,3 +123,31 @@ class DatesTests(TestCase):
		"year",
		order="bad order",
		)

		@override_settings(USE_TZ=False)
		def test_dates_trunc_datetime_fields(self):
		Article.objects.bulk_create(
		Article(pub_date=pub_datetime.date(), pub_datetime=pub_datetime)
		for pub_datetime in [
		datetime.datetime(2015, 10, 21, 18, 1),
		datetime.datetime(2015, 10, 21, 18, 2),
		datetime.datetime(2015, 10, 22, 18, 1),
		datetime.datetime(2015, 10, 22, 18, 2),
		]
		)
		self.assertQuerysetEqual(
		Article.objects.dates('pub_datetime', 'day', order='ASC'), [
		"datetime.date(2015, 10, 21)",
		"datetime.date(2015, 10, 22)",
		]
		)

		@skipUnless(connection.vendor == 'mysql', "Test checks MySQL query syntax")
		def test_dates_avoid_datetime_cast(self):
		Article.objects.create(pub_date=datetime.date(2015, 10, 21))
		for kind in ['day', 'month', 'year']:
		qs = Article.objects.dates('pub_date', kind)
		if kind == 'day':
		self.assertIn('DATE(', str(qs.query))
		else:
		self.assertIn(' AS DATE)', str(qs.query))