Fixed #32786 -- Moved subquery ordering clearing optimization to the _in lookup.

Co-Authored-By: Simon Charette <charette.s@gmail.com>

django/db/backends/base/features.py

@@ -64,6 +64,9 @@ class BaseDatabaseFeatures:
     has_real_datatype = False
     supports_subqueries_in_group_by = True
 
+    # Does the backend ignore unnecessary ORDER BY clauses in subqueries?
+    ignores_unnecessary_order_by_in_subqueries = True
+
     # Is there a true datatype for uuid?
     has_native_uuid_field = False
 

django/db/backends/oracle/features.py

@@ -15,6 +15,7 @@ class DatabaseFeatures(BaseDatabaseFeatures):
     select_for_update_of_column = True
     can_return_columns_from_insert = True
     supports_subqueries_in_group_by = False
+    ignores_unnecessary_order_by_in_subqueries = False
     supports_transactions = True
     supports_timezones = False
     has_native_duration_field = True

django/db/models/lookups.py

@@ -404,9 +404,16 @@ class In(FieldGetDbPrepValueIterableMixin, BuiltinLookup):
             placeholder = '(' + ', '.join(sqls) + ')'
             return (placeholder, sqls_params)
         else:
-            if not getattr(self.rhs, 'has_select_fields', True):
-                self.rhs.clear_select_clause()
-                self.rhs.add_fields(['pk'])
+            from django.db.models.sql.query import (  # avoid circular import
+                Query,
+            )
+            if isinstance(self.rhs, Query):
+                query = self.rhs
+                query.clear_ordering(clear_default=True)
+                if not query.has_select_fields:
+                    query.clear_select_clause()
+                    query.add_fields(['pk'])
+
             return super().process_rhs(compiler, connection)
 
     def get_group_by_cols(self, alias=None):

django/db/models/sql/query.py

@@ -1034,12 +1034,6 @@ class Query(BaseExpression):
         # Subqueries need to use a different set of aliases than the outer query.
         clone.bump_prefix(query)
         clone.subquery = True
-        # It's safe to drop ordering if the queryset isn't using slicing,
-        # distinct(*fields) or select_for_update().
-        if (self.low_mark == 0 and self.high_mark is None and
-                not self.distinct_fields and
-                not self.select_for_update):
-            clone.clear_ordering(force=True)
         clone.where.resolve_expression(query, *args, **kwargs)
         for key, value in clone.annotations.items():
             resolved = value.resolve_expression(query, *args, **kwargs)
@@ -1062,6 +1056,13 @@ class Query(BaseExpression):
         ]
 
     def as_sql(self, compiler, connection):
+        # Some backends (e.g. Oracle) raise an error when a subquery contains
+        # unnecessary ORDER BY clause.
+        if (
+            self.subquery and
+            not connection.features.ignores_unnecessary_order_by_in_subqueries
+        ):
+            self.clear_ordering(force=False)
         sql, params = self.get_compiler(connection=connection).as_sql()
         if self.subquery:
             sql = '(%s)' % sql

django/db/models/sql/where.py

@@ -239,6 +239,7 @@ class SubqueryConstraint:
         self.alias = alias
         self.columns = columns
         self.targets = targets
+        query_object.clear_ordering(clear_default=True)
         self.query_object = query_object
 
     def as_sql(self, compiler, connection):

tests/postgres_tests/test_aggregates.py

@@ -1,4 +1,6 @@
-from django.db.models import CharField, F, OuterRef, Q, Subquery, Value
+from django.db.models import (
+    CharField, F, Func, IntegerField, OuterRef, Q, Subquery, Value,
+)
 from django.db.models.fields.json import KeyTextTransform, KeyTransform
 from django.db.models.functions import Cast, Concat, Substr
 from django.test.utils import Approximate
@@ -12,6 +14,7 @@ try:
         RegrAvgX, RegrAvgY, RegrCount, RegrIntercept, RegrR2, RegrSlope,
         RegrSXX, RegrSXY, RegrSYY, StatAggregate, StringAgg,
     )
+    from django.contrib.postgres.fields import ArrayField
 except ImportError:
     pass  # psycopg2 is not installed
 
@@ -390,6 +393,20 @@ class TestGeneralAggregate(PostgreSQLTestCase):
             [self.aggs[0]],
         )
 
+    def test_ordering_isnt_cleared_for_array_subquery(self):
+        inner_qs = AggregateTestModel.objects.order_by('-integer_field')
+        qs = AggregateTestModel.objects.annotate(
+            integers=Func(
+                Subquery(inner_qs.values('integer_field')),
+                function='ARRAY',
+                output_field=ArrayField(base_field=IntegerField()),
+            ),
+        )
+        self.assertSequenceEqual(
+            qs.first().integers,
+            inner_qs.values_list('integer_field', flat=True),
+        )
+
 
 class TestAggregateDistinct(PostgreSQLTestCase):
     @classmethod