https://github.com/rails/rails/pull/36350

benchmark_pluck.rb

# frozen_string_literal: true

require "bundler/inline"

gemfile(true) do
  source "https://rubygems.org"

  git_source(:github) { |repo| "https://github.com/#{repo}.git" }

  gem "rails", github: "rails/rails"
  gem "sqlite3"
  gem "benchmark-ips"
end

require "active_record"

ActiveRecord::Base.establish_connection(adapter: "sqlite3", database: ":memory:")

ActiveRecord::Schema.define do
  create_table :users, force: true do |t|
    t.string :name
    t.timestamps null: false
  end
end

class User < ActiveRecord::Base
end

users = User.all

Benchmark.ips do |x|
  x.report("users.pluck(:id)") { users.pluck(:id) }
  x.report("users.order(:id).to_sql") { users.order(:id).to_sql }
end