Benchmark for native timestamp conversion on PostgreSQL adapter

pg-native-timestamps.rb

# frozen_string_literal: true

require 'bundler/inline'

gemfile do
  source 'https://rubygems.org'
  gem 'pg', '~> 1.1'
  gem 'activerecord', path: '../activerecord'
  gem 'benchmark-ips'
end

require 'active_record'
require 'benchmark/ips'


ActiveRecord::Base.establish_connection(
  :adapter => "postgresql",
  :database => "test_db"
)

pg = ActiveRecord::Base.connection.raw_connection

pg.async_exec <<SQL
drop table if exists topics
SQL

pg.async_exec <<SQL
CREATE TABLE topics (
    id integer NOT NULL,
    title character varying NOT NULL,
    last_posted_at timestamp without time zone,
    created_at timestamp without time zone NOT NULL,
    updated_at timestamp without time zone NOT NULL
)
SQL

class Topic < ActiveRecord::Base
end

Topic.transaction do
  topic = {
  }
  Topic.columns.each do |c|
    topic[c.name.to_sym] = case c.type
                           when :integer then 1
                           when :datetime then Time.now
                           else "HELLO WORLD"
                           end
  end

  2000.times do |id|
    topic[:id] = id
    Topic.create!(topic)
  end
end

def top_1000
  a = []
  Topic.limit(1000).each do |t|
    a << t.attributes
  end
  a
end

Benchmark.ips do |x|
  x.report("top_1000") do |i|
    while i > 0
      top_1000
      i -= 1
    end
  end
end

# rails branch master:
#
# Warming up --------------------------------------
#             top_1000     2.000  i/100ms
# Calculating -------------------------------------
#             top_1000     22.378  (± 0.0%) i/s -    112.000  in   5.006214s
#
# rails branch native-timestamps:
#
# Warming up --------------------------------------
#             top_1000     3.000  i/100ms
# Calculating -------------------------------------
#             top_1000     39.373  (± 2.5%) i/s -    198.000  in   5.030601s