Upgrade guide. Renaming Indexes on tables. [ci skip].

https://github.com/rails/rails/commit/39eef1a565ef02e4dabc0811ef1bf4547ff9a60e#commitcomment-3672522

1 files changed, 2 insertions, 0 deletions

diff --git a/guides/source/upgrading_ruby_on_rails.md b/guides/source/upgrading_ruby_on_rails.md
index 06798faa98..b7ec747a77 100644
--- a/guides/source/upgrading_ruby_on_rails.md
+++ b/guides/source/upgrading_ruby_on_rails.md
@@ -151,6 +151,8 @@ Rails 4.0 no longer supports loading plugins from `vendor/plugins`. You must rep
 
 * The `delete` method in collection associations can now receive `Fixnum` or `String` arguments as record ids, besides records, pretty much like the `destroy` method does. Previously it raised `ActiveRecord::AssociationTypeMismatch` for such arguments. From Rails 4.0 on `delete` automatically tries to find the records matching the given ids before deleting them.
 
+* In Rails 4.0 when a column or a table is renamed the related indexes are also renamed. If you have migrations which rename the indexes, they are no longer needed.
+
 * Rails 4.0 has changed how orders get stacked in `ActiveRecord::Relation`. In previous versions of Rails, the new order was applied after the previously defined order. But this is no longer true. Check [Active Record Query guide](active_record_querying.html#ordering) for more information.
 
 * Rails 4.0 has changed `serialized_attributes` and `attr_readonly` to class methods only. You shouldn't use instance methods since it's now deprecated. You should change them to use class methods, e.g. `self.serialized_attributes` to `self.class.serialized_attributes`.