* Replace incorrect use of distinct with group
Some uses of ActiveRecord::QueryMethods#distinct pass field names but they
are incorrect for the current version of Rails.
ActiveRecord::QueryMethods#group provides the expected behavior and
benefits performance. See commit 6da24aad4c.
* Introduce ApplicationController#cache_collection_paginated_by_id
ApplicationController#cache_collection_paginated_by_id fuses
ApplicationController#cache_collection and Paginable.paginate_by_id.
An advantage of this method is that it prevents from modifying scope which
Paginable.paginate_by_id may provide.
ApplicationController#cache_collection always return an array and there
is no possibility of the scope modification. It is also clear for a
programmer, considering the implication of "cache".
This method can also emit more efficient queries by using
Cacheable.cache_ids before calling Paginable.paginate_by_id.
Akihiko Odaki