Postgres query service should use find_each in #find_all and #find_all_of_model for efficiency

[dchandekstark]

https://api.rubyonrails.org/classes/ActiveRecord/Batches.html#method-i-find_each

For example, current code using .all:

    def find_all
      orm_class.all.lazy.map do |orm_object|
        resource_factory.to_resource(object: orm_object)
      end
    end

Could be updated to

    def find_all
      orm_class.find_each.lazy.map do |orm_object|
        resource_factory.to_resource(object: orm_object)
      end
    end

#find_all_of_model has a where clause, but it could still benefit from find_each since that can be a large query.

[tpendragon]

Yeah that sounds great! We do something similar in the sequel plugin.