The issue

The definition of resources_find in ResourceAdapter uses (simplified) resources.select("table_name.*"). This hinders the ability of ActiveRecord to combine queries together, because the select is already supplied to select all fields, even when only some of them are needed.

The fix

As far as I understand, removing the complete line that supplies the select does not alter any behavior. It leaves it up to ActiveRecord to determine which fields are necessary for the query. It will default to * but can be limited to id when useful for combining queries. I will try to make a pull request (#580) to see if this is indeed the case in all scenarios. I have tested so far with MySQL and SQLite where it works, and I expect other implementations to behave the same.

A detailed example

Setup
Showing with an example, consider models User, Blog and Article:

class User < ActiveRecord::Base
  rolify
end

class Blog < ActiveRecord::Base
  ROLES = %i[editor].freeze
  resourcify

  has_many :articles
end

class Article < ActiveRecord::Base
  belongs_to :blog
end

Normal Behavior
In active record, the following works

Article.where(blog_id: Blog.where(<some conditions>))

These are (usually) combined into a single query. This is because ActiveRecord recognizes that we want only the ids of the blogs and effectively applies .select(:id). Contrast that with for example:

Article.where(blog_id: Blog.where(<some conditions>).ids)

Now we get 2 separate queries, once for all the ids of the blogs and then another query with the condition blog_id IN (... those ids ...).

So for efficiency sake (less requests to the database), the top way would be preferable.

Rolify
Unfortunatly, the rolify with_role has already specified a select * (in resources_find), and this breaks this functionality. For example:

Article.where(blog_id: Blog.with_role(:editor, user))

Gives an invalid SQL query. Similarly, applying .select(:id) has no effect and does not affect the (invalid) query (the former select seems to take precedence). The only resort is to use .ids, which splits it into 2 separate queries.

Versions

Rolify 6.0.0
ActiveRecord 6.1.4.6
All versions of Ruby