Performance of ActiveRecord-Setters

output (PostgreSQL)

          user        system     total       real
variable  1.590000    0.000000    1.590000   (  1.599274)
AR        69.490000   2.440000   71.930000   ( 71.920999)

AR is 44.97 times slower.

schema.rb

create_table :numeric_data, :force => true do |t|
  t.decimal :big_bank_balance, :precision => 15, :scale => 2
end

test_case.rb

require "cases/helper"

class PerformanceTest < ActiveRecord::TestCase

  class NumericData < ActiveRecord::Base; end

  def test_active_record_setter_performance
    require 'benchmark'

    data = NumericData.new(:big_bank_balance => 0)
    @big_bank_balance = BigDecimal.new('0')
    n = 1_000_000
    Benchmark.bm do |x|
      x.report('variable') { n.times { |i| @big_bank_balance += i } }
      x.report('AR') { n.times { |i| data.big_bank_balance += i } }
    end
  end
end