http://sulug.blogspot.com/2010/01/datamapper-threaded-repository-sample.html

dmmultitheaded.rb

=begin
datamapper threaded repository sample with multiple mysql databases
modelling mysql => User table can be used administering mysql
=end

require 'dm-core'

Servers = {
  :mysql1 => 'mysql1.foo.com',
  :mysql2 => 'mysql2.foo.com',
  :mysql3 => 'mysql3.foo.com',
  :mysql4 => 'mysql4.foo.com',
  :mysql5 => 'mysql5.foo.com',
  :mysql6 => 'mysql6.foo.com',
  :mysql7 => 'mysql7.foo.com',
  :mysql8 => 'mysql8.foo.com'
}

DataMapper::Logger.new(STDOUT, :debug)

class User
  include DataMapper::Resource

  Servers.each do |s,d|
    storage_names[s.to_sym] = 'user'
  end

  property :host, String, :field => 'Host', :default => 'localhost'
  property :user, String, :field => 'User', :required => true, :key => true
  property :password, String, :field => 'Password', :required => true

  before :save do
    self[:password] = self.repository.adapter.select("select password('#{self[:password]}')")[0]
  end

  after :save do
    self.repository.adapter.execute('flush privileges')
  end

end

Servers.each do |s, d|
  DataMapper.setup(s.to_sym, "mysql://root:****@#{d}/mysql")
end

def searchUserLike(query)
  thr = Array.new

  Servers.each do |s, d|
    thr << Thread.new do
      repository(s.to_sym) do
        user = User.all(:user.like => "#{query}")
        user.each {|u| puts u[:user] << '=>' << u.repository.name} if user
      end
    end
  end

  thr.each { |t| t.join}
end

irb session 1.rb

>> searchUserLike('test%')
test_modul=>mysql1
testuser=>mysql2
test55=>mysql4
testasarim-com=>mysql7
test=>mysql5
testturk=>mysql5
testturkticaret=>mysql5
=> [#<Thread:0x000000023eb440 dead>, #<Thread:0x000000023eae90 dead>, #<Thread:0x000000023eabb8 dead>, #<Thread:0x000000023ea6b0 dead>, #<Thread:0x000000023ea2c0 dead>, #<Thread:0x000000026a55a0 dead>, #<Thread:0x000000026a5450 dead>, #<Thread:0x000000026a5300 dead>]

irb session 2.rb

>> repository(:mysql5) {user = User.new(:user => 'selman', :password => 'selman'); user.save}
=> true
>> repository(:mysql5) {user = User.get('selman'); puts user[:user] << ' => ' << user[:password]}
selman => *095F8DE298368D30B240ED629533891525F59444
=> nil

load sample code;

[slmn@gabriel projects]$ irb -r dmmultitheaded.rb
>>