findする件数を小分けにしてくれるメソッド。
こんなのがあるとは知らなかった。
まさにバッチ用。
使い方
:batch_size オプションで件数を指定。selectしてupdateなど。
Product.find_in_batches(:batch_size => 10) do |batch| puts "Products in batch: #{batch.size}" end
ソース
.gem/ruby/1.8/gems/activerecord-2.3.10/lib/active_record/batches.rb
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