pluck_benchmark.rb

class CreateModels < ActiveRecord::Migration
  def change
    create_table :items do |t|
    end
  end
end

class Item < ActiveRecord::Base
end

CreateModels.new.change

puts "Populating Database"
1000.times do
  Item.create
end

require 'benchmark'
puts 'Performance testing'
Benchmark.bm do |x|
  x.report { 3.times { Item.pluck(:id) } }
end