Benchmark ActiveRecord::Associations::CollectionAssociation#delete

benchmark.rb

begin
  require "bundler/inline"
rescue LoadError => e
  $stderr.puts "Bundler version 1.10 or later is required. Please update your Bundler"
  raise e
end

gemfile(true) do
  source "https://rubygems.org"
  gem "rails", github: "rails/rails"
  gem "sqlite3"
  gem "benchmark-ips"
  gem "kalibera"
end

require "active_record"
require 'benchmark/ips'
require "logger"

ActiveRecord::Base.establish_connection(adapter: "sqlite3", database: ":memory:")
ActiveRecord::Base.logger = Logger.new(nil)

ActiveRecord::Schema.define do
  create_table :posts, force: true do |t|
  end
  create_table :comments, force: true do |t|
    t.integer :post_id
  end
end

class Post < ActiveRecord::Base
  has_many :comments
end

class Comment < ActiveRecord::Base
  belongs_to :post
end

post = Post.create!
comments = Comment.transaction do
  100.times.map { post.comments.create! }
end
rm_comments = comments.sample(50)

Benchmark.ips do |bm|
  bm.config(stats: :bootstrap)
  bm.report("deleting #{rm_comments.count} records") do
    post.comments.delete(*rm_comments)
  end
end