Refs #29182 -- Stopped relying on legacy alter table semantic on SQLi…

…te 3.26+.

SQLite 3.26 changed the behavior of table and column renaming operations to
repoint foreign key references even if foreign key checks are disabled.

This makes the workarounds in place to simulate this behavior unnecessary on
SQLite 3.26+. Refs #30033.

django/db/backends/sqlite3/features.py

@@ -25,7 +25,7 @@ class DatabaseFeatures(BaseDatabaseFeatures):
     supports_transactions = True
     atomic_transactions = False
     can_rollback_ddl = True
-    supports_atomic_references_rename = False
+    supports_atomic_references_rename = Database.version_info >= (3, 26, 0)
     supports_paramstyle_pyformat = False
     supports_sequence_reset = False
     can_clone_databases = True

django/db/backends/sqlite3/schema.py

@@ -27,13 +27,11 @@ def __enter__(self):
                 'SQLite3 does not support disabling them in the middle of '
                 'a multi-statement transaction.'
             )
-        self.connection.cursor().execute('PRAGMA legacy_alter_table = ON')
         return super().__enter__()
 
     def __exit__(self, exc_type, exc_value, traceback):
         super().__exit__(exc_type, exc_value, traceback)
         self.connection.check_constraints()
-        self.connection.cursor().execute('PRAGMA legacy_alter_table = OFF')
         self.connection.enable_constraint_checking()
 
     def quote_value(self, value):
@@ -84,11 +82,12 @@ def _is_referenced_by_fk_constraint(self, table_name, column_name=None, ignore_s
         return False
 
     def alter_db_table(self, model, old_db_table, new_db_table, disable_constraints=True):
-        if disable_constraints and self._is_referenced_by_fk_constraint(old_db_table):
+        if (not self.connection.features.supports_atomic_references_rename and
+                disable_constraints and self._is_referenced_by_fk_constraint(old_db_table)):
             if self.connection.in_atomic_block:
                 raise NotSupportedError((
                     'Renaming the %r table while in a transaction is not '
-                    'supported on SQLite because it would break referential '
+                    'supported on SQLite < 3.26 because it would break referential '
                     'integrity. Try adding `atomic = False` to the Migration class.'
                 ) % old_db_table)
             self.connection.enable_constraint_checking()
@@ -102,11 +101,12 @@ def alter_field(self, model, old_field, new_field, strict=False):
         table_name = model._meta.db_table
         _, old_column_name = old_field.get_attname_column()
         if (new_field.name != old_field_name and
+                not self.connection.features.supports_atomic_references_rename and
                 self._is_referenced_by_fk_constraint(table_name, old_column_name, ignore_self=True)):
             if self.connection.in_atomic_block:
                 raise NotSupportedError((
                     'Renaming the %r.%r column while in a transaction is not '
-                    'supported on SQLite because it would break referential '
+                    'supported on SQLite < 3.26 because it would break referential '
                     'integrity. Try adding `atomic = False` to the Migration class.'
                 ) % (model._meta.db_table, old_field_name))
             with atomic(self.connection.alias):

tests/backends/sqlite/tests.py

@@ -121,8 +121,8 @@ def test_field_rename_inside_atomic_block(self):
         new_field.set_attributes_from_name('renamed')
         msg = (
             "Renaming the 'backends_author'.'name' column while in a "
-            "transaction is not supported on SQLite because it would break "
-            "referential integrity. Try adding `atomic = False` to the "
+            "transaction is not supported on SQLite < 3.26 because it would "
+            "break referential integrity. Try adding `atomic = False` to the "
             "Migration class."
         )
         with self.assertRaisesMessage(NotSupportedError, msg):
@@ -136,7 +136,7 @@ def test_table_rename_inside_atomic_block(self):
         """
         msg = (
             "Renaming the 'backends_author' table while in a transaction is "
-            "not supported on SQLite because it would break referential "
+            "not supported on SQLite < 3.26 because it would break referential "
             "integrity. Try adding `atomic = False` to the Migration class."
         )
         with self.assertRaisesMessage(NotSupportedError, msg):