gistfile1.rb

require 'data_mapper'

# so we can see how long the database hits take.
DataMapper::Logger.new($stdout, :debug)
#DataMapper.setup(:default, "sqlite://#{File.expand_path(File.dirname(File.expand_path(__FILE__)) + '/data.db')}")

DataMapper.setup(:default, 'sqlite::memory:')

class Entry
  include DataMapper::Resource
  property :id,         Serial
  property :field,      Integer
end

DataMapper.finalize # finalizes changes to model structure for database.
DataMapper.auto_migrate! # structures database to fit the model

# create 5000 entries
5000.times { Entry.create }

# just access the field of a single entry
Entry.first.field

# does nothing but access each field
Entry.all.each &:field

# update a single field to a new value.
Entry.first.update({:field=>99999})