benchmark for find in batches

benchmark_find_in_batches.rb

require 'benchmark/ips'

Benchmark.ips do |x|
  x.config(:time => 5, :warmup => 2)

  x.report("select in batches and lookup using the id") do
    User.find_in_batches(:conditions => ["updated_at > ?", 8.weeks.ago.to_s(:db)], :select => :id) do |users|
      users.map { |user| User.find(user.id, :include => [:user_metric]).id }
    end
  end

  x.report("lookup in batches") do |times|
    User.find_in_batches(:conditions => ["updated_at > ?", 8.weeks.ago.to_s(:db)], :include => [:user_metric]) do |users|
      users.map { |user| user.id }
    end
  end

  x.compare!
end

output.rb

Calculating -------------------------------------
select in batches and lookup using the id
                        20.000  i/100ms
   lookup in batches    36.000  i/100ms
-------------------------------------------------
select in batches and lookup using the id
                        266.158  (±39.8%) i/s -      1.060k
   lookup in batches     21.686k (±12.7%) i/s -     64.728k

Comparison:
   lookup in batches:    21686.5 i/s
select in batches and lookup using the id:      266.2 i/s - 81.48x slower

Installation

gem install benchmark-ips