chunky_each.rb

# Example activerecord interator based on using an indexed 'id' column.
# See http://schuerig.de/michael/blog/index.php/2007/02/03/ar-enumerable/
# and http://weblog.jamisbuck.org/2007/4/6/faking-cursors-in-activerecord

class << ActiveRecord::Base
  def each(chunk_size=1000)
    (0..self.last.id / chunk_size).each do |offset|
      self.find(:all,
        :limit => chunk_size,
        :conditions => ["id > ?", offset * chunk_size]).each do |i|
        yield i
      end
    end
  end
end