Performance on selecting all columns instead of specified attributes

Is there a reason the _model_class queries all columns?

https://github.com/cerebris/jsonapi-resources/blob/bf4b4cd7d79da453372880068e167066f0d05f47/lib/jsonapi/active_relation_resource.rb#L286-L288

This is a huge performance impact on models with many columns that may not ever be used by the resource.

It seems for performance reasons it makes sense to only select the attributes defined in the JSONAPI::Resource class.

A workaround for now is to override each resource using .select to retrieve only the fields that are specifically defined.

attributes :name, :address

def self.records(_options = {})
  super.select(self.fields)
end

This should also take into account sparse fieldsets parameters, which would further limit which columns are selected.

Start in lib/jsonapi/active_relation_resource.rb at the linked _model_class query and trace how Resource attributes and sparse fieldsets are represented. The work is done when those queries select only the fields needed by the resource and request fieldset, while preserving the existing records behavior and covering the relevant query paths.