#coding=utf-8
require 'sequel'
require 'singleton'

class Database
  include Singleton
  attr_reader :conn

  def initialize
    servers =  {
        :shard_1 => {:database=>'part01'},
        :shard_2 => {:database=>'part02'}
    }
    @conn = Sequel.postgres(:host =>'localhost', :user => '', :password => '', :database=>'part01', :servers => servers, :single_threaded => :true, :max_connections => 1)
  end

end

pids = []
2.times do
  pids << fork do
    Database.instance.conn.transaction(:server => :shard_2) do |c|
      Database.instance.conn['SELECT pg_sleep(5)'].single_value # ??????????
    end
  end
end
pids.each {|p| Process.wait(p)}