module ActiveRecord::Batches::ClassMethods

def batch_order 

def batch_order
  "#{table_name}.#{primary_key} ASC"
end

def find_each(options = {})

better just to use the regular find methods.
you just need to loop over less than 1000 records, it's probably
large amounts of records that wouldn't fit in memory all at once. If
Note: This method is only intended to use for batch processing of

end
person.party_all_night!
Person.find_each(:conditions => "age > 21") do |person|

Example:

specified by the :batch_size option).
performed by find_in_batches with a batch size of 1000 (or as
Yields each record that was found by the find +options+. The find is 
def find_each(options = {})
  find_in_batches(options) do |records|
    records.each { |record| yield record }
  end
  self
end

def find_in_batches(options = {})

end
group.each { |person| person.party_all_night! }
sleep(50) # Make sure it doesn't get too crowded in there!
Person.find_in_batches(:conditions => "age > 21") do |group|

Example:

the the batch sizes.
primary keys. You can't set the limit either, that's used to control
work. This also mean that this method only works with integer-based
ascending on the primary key ("id ASC") to make the batch ordering
It's not possible to set the order. That is automatically set to

option on that worker).
worker 2 handle from 10,000 and beyond (by setting the :start
make worker 1 handle all the records between id 0 and 10,000 and
want multiple workers dealing with the same processing queue. You can
supplying the :start option. This is especially useful if you
You can control the starting point for the batch processing by

option; the default is 1000.
an array. The size of each batch is set by the :batch_size
Yields each batch of records that was found by the find +options+ as 
def find_in_batches(options = {})
  raise "You can't specify an order, it's forced to be #{batch_order}" if options[:order]
  raise "You can't specify a limit, it's forced to be the batch_size"  if options[:limit]
  start = options.delete(:start).to_i
  batch_size = options.delete(:batch_size) || 1000
  proxy = scoped(options.merge(:order => batch_order, :limit => batch_size))
  records = proxy.find(:all, :conditions => [ "#{table_name}.#{primary_key} >= ?", start ])
  while records.any?
    yield records
    break if records.size < batch_size
    
    last_value = records.last.id
    
    raise "You must include the primary key if you define a select" unless last_value.present?
    
    records = proxy.find(:all, :conditions => [ "#{table_name}.#{primary_key} > ?", last_value ])
  end
end