Comparing performance of Sequel and Active Record when fetching 1000 records

benchmark.rb

require "bundler/inline"

gemfile do
  source "https://rubygems.org"

  gem "activerecord", "6.0.3.3", require: "active_record"
  gem "sequel", "5.36"
  gem "sequel_pg", "1.13.0", require: false
  gem "pg", "1.2.3"
  gem "mysql2", "0.5.3"
  gem "benchmark-ips", require: "benchmark/ips"
  gem "memory_profiler"
end

CONFIGURATIONS = [
  { adapter: "postgresql", database: "sequel" },
  { adapter: "mysql2",     database: "sequel" },
]

Sequel.database_timezone = :utc # makes mysql2 client faster
Sequel::Model.cache_anonymous_models = false

def memory(name, &block)
  result = MemoryProfiler.report(&block)
  puts "#{name} – #{result.total_allocated} allocated objects"
end

CONFIGURATIONS.each do |configuration|
  puts
  puts "Database configuration: #{configuration}"

  db = Sequel.connect(**configuration, keep_reference: false)
  ActiveRecord::Base.establish_connection(**configuration)

  db.create_table! :articles do
    primary_key :id

    String  :title
    String  :body
    Boolean :published

    Integer :read_count
    Integer :comment_count
    Integer :position

    Time :created_at
    Time :updated_at
    Time :published_at
  end

  # insert 1000 dummy records
  db[:articles].multi_insert Array.new(1000, {
    title:         "My title",
    body:          "My longer descriptive body",
    published:     true,
    read_count:    123948,
    comment_count: 123,
    created_at:    Sequel::CURRENT_TIMESTAMP,
    updated_at:    Sequel::CURRENT_TIMESTAMP,
    published_at:  Sequel::CURRENT_TIMESTAMP,
  })

  activerecord_model = Class.new(ActiveRecord::Base) { self.table_name = :articles }
  sequel_model       = Sequel::Model(db[:articles])

  Benchmark.ips do |x|
    x.config(warmup: 5, time: 20)

    x.report("activerecord (w/o reading)") { activerecord_model.all.to_a               }
    x.report("activerecord (w/  reading)") { activerecord_model.all.each(&:attributes) }
    x.report("sequel       (w/o reading)") { sequel_model.all                          }
    x.report("sequel       (w/  reading)") { sequel_model.all.each(&:values)           }

    x.compare!
  end

  memory("activerecord (w/o reading)") { activerecord_model.all.to_a               }
  memory("activerecord (w/  reading)") { activerecord_model.all.each(&:attributes) }
  memory("sequel       (w/o reading)") { sequel_model.all                          }
  memory("sequel       (w/  reading)") { sequel_model.all.each(&:values)           }
ensure
  ActiveRecord::Base.remove_connection
  db.disconnect
end