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Refs #17144 -- Removed support for grouping by primary key.

No core backend require the feature anymore as it was only added to
support a MySQL'ism that has been deprecated since then.
This commit is contained in:
Simon Charette 2022-11-05 12:49:33 -04:00 committed by Mariusz Felisiak
parent 041551d716
commit 5f09ab8c30
5 changed files with 15 additions and 61 deletions

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@ -8,7 +8,6 @@ class BaseDatabaseFeatures:
gis_enabled = False gis_enabled = False
# Oracle can't group by LOB (large object) data types. # Oracle can't group by LOB (large object) data types.
allows_group_by_lob = True allows_group_by_lob = True
allows_group_by_pk = False
allows_group_by_selected_pks = False allows_group_by_selected_pks = False
allows_group_by_refs = True allows_group_by_refs = True
empty_fetchmany_value = [] empty_fetchmany_value = []

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@ -179,41 +179,10 @@ class SQLCompiler:
return result return result
def collapse_group_by(self, expressions, having): def collapse_group_by(self, expressions, having):
# If the DB can group by primary key, then group by the primary key of # If the database supports group by functional dependence reduction,
# query's main model. Note that for PostgreSQL the GROUP BY clause must # then the expressions can be reduced to the set of selected table
# include the primary key of every table, but for MySQL it is enough to # primary keys as all other columns are functionally dependent on them.
# have the main table's primary key. if self.connection.features.allows_group_by_selected_pks:
if self.connection.features.allows_group_by_pk:
# Determine if the main model's primary key is in the query.
pk = None
for expr in expressions:
# Is this a reference to query's base table primary key? If the
# expression isn't a Col-like, then skip the expression.
if (
getattr(expr, "target", None) == self.query.model._meta.pk
and getattr(expr, "alias", None) == self.query.base_table
):
pk = expr
break
# If the main model's primary key is in the query, group by that
# field, HAVING expressions, and expressions associated with tables
# that don't have a primary key included in the grouped columns.
if pk:
pk_aliases = {
expr.alias
for expr in expressions
if hasattr(expr, "target") and expr.target.primary_key
}
expressions = [pk] + [
expr
for expr in expressions
if expr in having
or (
getattr(expr, "alias", None) is not None
and expr.alias not in pk_aliases
)
]
elif self.connection.features.allows_group_by_selected_pks:
# Filter out all expressions associated with a table's primary key # Filter out all expressions associated with a table's primary key
# present in the grouped columns. This is done by identifying all # present in the grouped columns. This is done by identifying all
# tables that have their primary key included in the grouped # tables that have their primary key included in the grouped

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@ -309,7 +309,12 @@ Database backend API
This section describes changes that may be needed in third-party database This section describes changes that may be needed in third-party database
backends. backends.
* ... * ``DatabaseFeatures.allows_group_by_pk`` is removed as it only remained to
accommodate a MySQL extension that has been supplanted by proper functional
dependency detection in MySQL 5.7.15. Note that
``DatabaseFeatures.allows_group_by_selected_pks`` is still supported and
should be enabled if your backend supports functional dependency detection in
``GROUP BY`` clauses as specified by the ``SQL:1999`` standard.
Dropped support for MariaDB 10.3 Dropped support for MariaDB 10.3
-------------------------------- --------------------------------

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@ -23,7 +23,7 @@ from django.db.models import (
Variance, Variance,
When, When,
) )
from django.test import TestCase, skipUnlessAnyDBFeature, skipUnlessDBFeature from django.test import TestCase, skipUnlessDBFeature
from django.test.utils import Approximate from django.test.utils import Approximate
from .models import ( from .models import (
@ -1420,7 +1420,7 @@ class AggregationTests(TestCase):
# The query executes without problems. # The query executes without problems.
self.assertEqual(len(qs.exclude(publisher=-1)), 6) self.assertEqual(len(qs.exclude(publisher=-1)), 6)
@skipUnlessAnyDBFeature("allows_group_by_pk", "allows_group_by_selected_pks") @skipUnlessDBFeature("allows_group_by_selected_pks")
def test_aggregate_duplicate_columns(self): def test_aggregate_duplicate_columns(self):
# Regression test for #17144 # Regression test for #17144
@ -1448,7 +1448,7 @@ class AggregationTests(TestCase):
], ],
) )
@skipUnlessAnyDBFeature("allows_group_by_pk", "allows_group_by_selected_pks") @skipUnlessDBFeature("allows_group_by_selected_pks")
def test_aggregate_duplicate_columns_only(self): def test_aggregate_duplicate_columns_only(self):
# Works with only() too. # Works with only() too.
results = Author.objects.only("id", "name").annotate( results = Author.objects.only("id", "name").annotate(
@ -1474,18 +1474,14 @@ class AggregationTests(TestCase):
], ],
) )
@skipUnlessAnyDBFeature("allows_group_by_pk", "allows_group_by_selected_pks") @skipUnlessDBFeature("allows_group_by_selected_pks")
def test_aggregate_duplicate_columns_select_related(self): def test_aggregate_duplicate_columns_select_related(self):
# And select_related() # And select_related()
results = Book.objects.select_related("contact").annotate( results = Book.objects.select_related("contact").annotate(
num_authors=Count("authors") num_authors=Count("authors")
) )
_, _, grouping = results.query.get_compiler(using="default").pre_sql_setup() _, _, grouping = results.query.get_compiler(using="default").pre_sql_setup()
# In the case of `group_by_selected_pks` we also group by contact.id self.assertEqual(len(grouping), 2)
# because of the select_related.
self.assertEqual(
len(grouping), 1 if connection.features.allows_group_by_pk else 2
)
self.assertIn("id", grouping[0][0]) self.assertIn("id", grouping[0][0])
self.assertNotIn("name", grouping[0][0]) self.assertNotIn("name", grouping[0][0])
self.assertNotIn("contact", grouping[0][0]) self.assertNotIn("contact", grouping[0][0])

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@ -550,21 +550,6 @@ class NonAggregateAnnotationTestCase(TestCase):
for publisher in publishers.filter(pk=self.p1.pk): for publisher in publishers.filter(pk=self.p1.pk):
self.assertEqual(publisher["book__rating"], publisher["total"]) self.assertEqual(publisher["book__rating"], publisher["total"])
@skipUnlessDBFeature("allows_group_by_pk")
def test_rawsql_group_by_collapse(self):
raw = RawSQL("SELECT MIN(id) FROM annotations_book", [])
qs = (
Author.objects.values("id")
.annotate(
min_book_id=raw,
count_friends=Count("friends"),
)
.order_by()
)
_, _, group_by = qs.query.get_compiler(using="default").pre_sql_setup()
self.assertEqual(len(group_by), 1)
self.assertNotEqual(raw, group_by[0])
def test_defer_annotation(self): def test_defer_annotation(self):
""" """
Deferred attributes can be referenced by an annotation, Deferred attributes can be referenced by an annotation,