Fixed -- Doc'd fast nullable column creation with defaults.
@@ -150,6 +150,21 @@ a default value to put into existing rows. It does not affect the behavior
of setting defaults in the database directly - Django never sets database
defaults and always applies them in the Django ORM code.
+.. warning::
+
+ On older databases, adding a field with a default value may cause a full
+ rewrite of the table. This happens even for nullable fields and may have a
+ negative performance impact. To avoid that, the following steps should be
+ taken.
+
+ * Add the nullable field without the default value and run the
+ :djadmin:`makemigrations` command. This should generate a migration with
+ an ``AddField`` operation.
+
+ * Add the default value to your field and run the :djadmin:`makemigrations`
+ command. This should generate a migration with an ``AlterField``
+ operation.
+
``RemoveField``
---------------
