construct_limited_ids_condition

# File activerecord/lib/active_record/relation/finder_methods.rb, line 232
    def construct_limited_ids_condition(relation)
      orders = relation.order_values.join(", ")
      values = @klass.connection.distinct("#{@klass.connection.quote_table_name @klass.table_name}.#{@klass.primary_key}", orders)

      ids_array = relation.select(values).collect {|row| row[@klass.primary_key]}
      ids_array.empty? ? raise(ThrowResult) : primary_key.in(ids_array)
    end