Fixed #25833 -- Added support for non-atomic migrations.

Added the Migration.atomic attribute which can be set to False
for non-atomic migrations.

1 files changed, 14 insertions, 6 deletions

diff --git a/docs/ref/migration-operations.txt b/docs/ref/migration-operations.txt
index e7fb9793e2..c8668d108e 100644
--- a/docs/ref/migration-operations.txt
+++ b/docs/ref/migration-operations.txt
@@ -269,7 +269,7 @@ be removed (elided) when :ref:`squashing migrations <migration-squashing>`.
 ``RunPython``
 -------------
 
-.. class:: RunPython(code, reverse_code=None, atomic=True, hints=None, elidable=False)
+.. class:: RunPython(code, reverse_code=None, atomic=None, hints=None, elidable=False)
 
 Runs custom Python code in a historical context. ``code`` (and ``reverse_code``
 if supplied) should be callable objects that accept two arguments; the first is
@@ -354,16 +354,19 @@ the ``schema_editor`` provided on these backends; in this case, pass
 
 On databases that do support DDL transactions (SQLite and PostgreSQL),
 ``RunPython`` operations do not have any transactions automatically added
-besides the transactions created for each migration (the ``atomic`` parameter
-has no effect on these databases). Thus, on PostgreSQL, for example, you should
-avoid combining schema changes and ``RunPython`` operations in the same
-migration or you may hit errors like ``OperationalError: cannot ALTER TABLE
-"mytable" because it has pending trigger events``.
+besides the transactions created for each migration. Thus, on PostgreSQL, for
+example, you should avoid combining schema changes and ``RunPython`` operations
+in the same migration or you may hit errors like ``OperationalError: cannot
+ALTER TABLE "mytable" because it has pending trigger events``.
 
 If you have a different database and aren't sure if it supports DDL
 transactions, check the ``django.db.connection.features.can_rollback_ddl``
 attribute.
 
+If the ``RunPython`` operation is part of a :ref:`non-atomic migration
+<non-atomic-migrations>`, the operation will only be executed in a transaction
+if ``atomic=True`` is passed to the ``RunPython`` operation.
+
 .. warning::
 
     ``RunPython`` does not magically alter the connection of the models for you;
@@ -382,6 +385,11 @@ attribute.
 
     The ``elidable`` argument was added.
 
+.. versionchanged:: 1.10
+
+    The ``atomic`` argument default was changed to ``None``, indicating that
+    the atomicity is controlled by the ``atomic`` attribute of the migration.
+
 ``SeparateDatabaseAndState``
 ----------------------------