instance method batch_on_unloaded_relation

# File activerecord/lib/active_record/relation/batches.rb, line 370
      def batch_on_unloaded_relation(relation:, start:, finish:, load:, order:, use_ranges:, remaining:, batch_limit:)
        batch_orders = build_batch_orders(order)
        relation = relation.reorder(batch_orders.to_h).limit(batch_limit)
        relation = apply_limits(relation, start, finish, batch_orders)
        relation.skip_query_cache! # Retaining the results in the query cache would undermine the point of batching
        batch_relation = relation
        empty_scope = to_sql == klass.unscoped.all.to_sql

        loop do
          if load
            records = batch_relation.records
            ids = records.map(&:id)
            yielded_relation = where(primary_key => ids)
            yielded_relation.load_records(records)
          elsif (empty_scope && use_ranges != false) || use_ranges
            ids = batch_relation.ids
            finish = ids.last
            if finish
              yielded_relation = apply_finish_limit(batch_relation, finish, batch_orders)
              yielded_relation = yielded_relation.except(:limit, :order)
              yielded_relation.skip_query_cache!(false)
            end
          else
            ids = batch_relation.ids
            yielded_relation = where(primary_key => ids)
          end

          break if ids.empty?

          primary_key_offset = ids.last
          raise ArgumentError.new("Primary key not included in the custom select clause") unless primary_key_offset

          yield yielded_relation

          break if ids.length < batch_limit

          if limit_value
            remaining -= ids.length

            if remaining == 0
              # Saves a useless iteration when the limit is a multiple of the
              # batch size.
              break
            elsif remaining < batch_limit
              relation = relation.limit(remaining)
            end
          end

          batch_orders_copy = batch_orders.dup
          _last_column, last_order = batch_orders_copy.pop
          operators = batch_orders_copy.map do |_column, order|
            order == :desc ? :lteq : :gteq
          end
          operators << (last_order == :desc ? :lt : :gt)

          batch_relation = batch_condition(relation, primary_key, primary_key_offset, operators)
        end

        nil
      end