aggregate_column

# File activerecord/lib/active_record/relation/calculations.rb, line 409
      def aggregate_column(column_name)
        return column_name if Arel::Expressions === column_name

        arel_column(column_name.to_s) do |name|
          column_name == :all ? Arel.sql("*", retryable: true) : Arel.sql(name)
        end
      end