Fixed #32120 -- Added DatabaseFeatures.indexes_foreign_keys.

3 files changed, 36 insertions, 9 deletions

diff --git a/django/db/backends/base/features.py b/django/db/backends/base/features.py
index 477ae96c8d..0b315aac02 100644
--- a/django/db/backends/base/features.py
+++ b/django/db/backends/base/features.py
@@ -172,6 +172,9 @@ class BaseDatabaseFeatures:
     # Can it create foreign key constraints inline when adding columns?
     can_create_inline_fk = True
 
+    # Does it automatically index foreign keys?
+    indexes_foreign_keys = True
+
     # Does it support CHECK constraints?
     supports_column_check_constraints = True
     supports_table_check_constraints = True
diff --git a/tests/introspection/tests.py b/tests/introspection/tests.py
index fd7def1def..82a661a83d 100644
--- a/tests/introspection/tests.py
+++ b/tests/introspection/tests.py
@@ -206,17 +206,20 @@ class IntrospectionTests(TransactionTestCase):
             constraints = connection.introspection.get_constraints(cursor, Article._meta.db_table)
         indexes_verified = 0
         expected_columns = [
-            ['reporter_id'],
             ['headline', 'pub_date'],
-            ['response_to_id'],
             ['headline', 'response_to_id', 'pub_date', 'reporter_id'],
         ]
+        if connection.features.indexes_foreign_keys:
+            expected_columns += [
+                ['reporter_id'],
+                ['response_to_id'],
+            ]
         for val in constraints.values():
             if val['index'] and not (val['primary_key'] or val['unique']):
                 self.assertIn(val['columns'], expected_columns)
                 self.assertEqual(val['orders'], ['ASC'] * len(val['columns']))
                 indexes_verified += 1
-        self.assertEqual(indexes_verified, 4)
+        self.assertEqual(indexes_verified, len(expected_columns))
 
     def test_get_constraints(self):
         def assertDetails(details, cols, primary_key=False, unique=False, index=False, check=False, foreign_key=None):
diff --git a/tests/schema/tests.py b/tests/schema/tests.py
index e41db7a500..a7743deba4 100644
--- a/tests/schema/tests.py
+++ b/tests/schema/tests.py
@@ -292,7 +292,12 @@ class SchemaTests(TransactionTestCase):
         with connection.schema_editor() as editor:
             editor.add_field(Node, new_field)
             editor.execute('UPDATE schema_node SET new_parent_fk_id = %s;', [parent.pk])
-        self.assertIn('new_parent_fk_id', self.get_indexes(Node._meta.db_table))
+        assertIndex = (
+            self.assertIn
+            if connection.features.indexes_foreign_keys
+            else self.assertNotIn
+        )
+        assertIndex('new_parent_fk_id', self.get_indexes(Node._meta.db_table))
 
     @skipUnlessDBFeature(
         'can_create_inline_fk',
@@ -316,7 +321,12 @@ class SchemaTests(TransactionTestCase):
             Node._meta.add_field(new_field)
             editor.execute('UPDATE schema_node SET new_parent_fk_id = %s;', [parent.pk])
             editor.add_index(Node, Index(fields=['new_parent_fk'], name='new_parent_inline_fk_idx'))
-        self.assertIn('new_parent_fk_id', self.get_indexes(Node._meta.db_table))
+        assertIndex = (
+            self.assertIn
+            if connection.features.indexes_foreign_keys
+            else self.assertNotIn
+        )
+        assertIndex('new_parent_fk_id', self.get_indexes(Node._meta.db_table))
 
     @skipUnlessDBFeature('supports_foreign_keys')
     def test_char_field_with_db_index_to_fk(self):
@@ -1161,6 +1171,7 @@ class SchemaTests(TransactionTestCase):
             editor.create_model(Author)
             editor.create_model(Book)
         expected_fks = 1 if connection.features.supports_foreign_keys else 0
+        expected_indexes = 1 if connection.features.indexes_foreign_keys else 0
 
         # Check the index is right to begin with.
         counts = self.get_constraints_count(
@@ -1168,7 +1179,10 @@ class SchemaTests(TransactionTestCase):
             Book._meta.get_field('author').column,
             (Author._meta.db_table, Author._meta.pk.column),
         )
-        self.assertEqual(counts, {'fks': expected_fks, 'uniques': 0, 'indexes': 1})
+        self.assertEqual(
+            counts,
+            {'fks': expected_fks, 'uniques': 0, 'indexes': expected_indexes},
+        )
 
         old_field = Book._meta.get_field('author')
         new_field = OneToOneField(Author, CASCADE)
@@ -1189,6 +1203,7 @@ class SchemaTests(TransactionTestCase):
             editor.create_model(Author)
             editor.create_model(Book)
         expected_fks = 1 if connection.features.supports_foreign_keys else 0
+        expected_indexes = 1 if connection.features.indexes_foreign_keys else 0
 
         # Check the index is right to begin with.
         counts = self.get_constraints_count(
@@ -1196,7 +1211,10 @@ class SchemaTests(TransactionTestCase):
             Book._meta.get_field('author').column,
             (Author._meta.db_table, Author._meta.pk.column),
         )
-        self.assertEqual(counts, {'fks': expected_fks, 'uniques': 0, 'indexes': 1})
+        self.assertEqual(
+            counts,
+            {'fks': expected_fks, 'uniques': 0, 'indexes': expected_indexes},
+        )
 
         old_field = Book._meta.get_field('author')
         # on_delete changed from CASCADE.
@@ -1211,7 +1229,10 @@ class SchemaTests(TransactionTestCase):
             (Author._meta.db_table, Author._meta.pk.column),
         )
         # The index remains.
-        self.assertEqual(counts, {'fks': expected_fks, 'uniques': 0, 'indexes': 1})
+        self.assertEqual(
+            counts,
+            {'fks': expected_fks, 'uniques': 0, 'indexes': expected_indexes},
+        )
 
     def test_alter_field_o2o_to_fk(self):
         with connection.schema_editor() as editor:
@@ -2521,7 +2542,7 @@ class SchemaTests(TransactionTestCase):
             with self.assertRaisesMessage(TransactionManagementError, message):
                 editor.execute(editor.sql_create_table % {'table': 'foo', 'definition': ''})
 
-    @skipUnlessDBFeature('supports_foreign_keys')
+    @skipUnlessDBFeature('supports_foreign_keys', 'indexes_foreign_keys')
     def test_foreign_key_index_long_names_regression(self):
         """
         Regression test for #21497.