DataMapper join tables

gistfile1.txt

require 'rubygems'
require 'dm-core'
require 'dm-migrations'
require 'dm-mysql-adapter'
require 'ffaker'
require 'benchmark'

logger = DataMapper::Logger.new(STDOUT, :debug)
DataMapper.setup(:default, 'mysql://dm:dm@localhost/dm_join_tables')

class Left 
  include DataMapper::Resource 
  property :id, Serial 
  has n, :joins 
  has n, :rights, :through => :joins 
end

class Join 
  include DataMapper::Resource 
  belongs_to :left,  :key => true 
  belongs_to :right, :key => true 
end

class Right 
  include DataMapper::Resource 
  property :id, Serial 
  property :one, String 
  property :two, Integer
  property :three, Text
end

DataMapper.finalize

unless ARGV.include? '--only-queries'
  DataMapper.auto_migrate!

  puts '==================================='
  logger.level = DataMapper::Logger::Levels[:warn]

  1000.times do |i|
    Right.create :one => 'foo', :two => i, :three => Faker::Lorem.paragraphs(10)
  end
  all_rights = Right.all.to_a

  1000.times do |i|
    Left.create :rights => (rand * 10).to_i.times.map {|i| all_rights.sample}
  end

  logger.level = DataMapper::Logger::Levels[:debug]
end

puts '==================================='

logger.level = DataMapper::Logger::Levels[:warn]

n = 5000
Benchmark.bm(10) do |x|
  x.report('single: ') { n.times {Left.first.rights.to_a} }
  x.report('split:  ') { n.times {Left.first.joins.rights.to_a} }
end