instance method `find_in_batches`

Ruby on Rails 3.1.12

Since v3.1.12

Available in: v3.1.12 v3.2.22.5 v4.0.13 v4.1.16 v4.2.9 v5.2.8.1 v6.0.6 v6.1.7.10 v7.0.10 v7.1.6 v7.2.3 v8.0.4 v8.1.2

Compare with:

find_in_batches(options = {})

Yields each batch of records that was found by the find options as an array. The size of each batch is set by the :batch_size option; the default is 1000.

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

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

Example:

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

Parameters

options opt = {}

Source

# File activerecord/lib/active_record/relation/batches.rb, line 48
    def find_in_batches(options = {})
      relation = self

      unless arel.orders.blank? && arel.taken.blank?
        ActiveRecord::Base.logger.warn("Scoped order and limit are ignored, it's forced to be batch order and batch size")
      end

      if (finder_options = options.except(:start, :batch_size)).present?
        raise "You can't specify an order, it's forced to be #{batch_order}" if options[:order].present?
        raise "You can't specify a limit, it's forced to be the batch_size"  if options[:limit].present?

        relation = apply_finder_options(finder_options)
      end

      start = options.delete(:start).to_i
      batch_size = options.delete(:batch_size) || 1000

      relation = relation.reorder(batch_order).limit(batch_size)
      records = relation.where(table[primary_key].gteq(start)).all

      while records.any?
        yield records

        break if records.size < batch_size

        if primary_key_offset = records.last.id
          records = relation.where(table[primary_key].gt(primary_key_offset)).to_a
        else
          raise "Primary key not included in the custom select clause"
        end
      end
    end

Defined in activerecord/lib/active_record/relation/batches.rb line 48 · View on GitHub · Improve this page · Find usages on GitHub

Defined in ActiveRecord::Batches

Signature

Parameters