instance method `find_in_batches`

Ruby on Rails 4.2.9

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.

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

If you do not provide a block to #find_in_batches, it will return an Enumerator for chaining with other methods:

Person.find_in_batches.with_index do |group, batch|
  puts "Processing group ##{batch}"
  group.each(&:recover_from_last_night!)
end

To be yielded each record one by one, use #find_each instead.

Options

:batch_size - Specifies the size of the batch. Default to 1000.
:start - Specifies the starting point for the batch processing.

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).

# Let's process the next 2000 records
Person.find_in_batches(start: 2000, batch_size: 2000) do |group|
  group.each { |person| person.party_all_night! }
end

NOTE: 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 means that this method only works with integer-based primary keys.

NOTE: You can’t set the limit either, that’s used to control the batch sizes.

Parameters

options opt = {}

Source

# File activerecord/lib/active_record/relation/batches.rb, line 98
    def find_in_batches(options = {})
      options.assert_valid_keys(:start, :batch_size)

      relation = self
      start = options[:start]
      batch_size = options[:batch_size] || 1000

      unless block_given?
        return to_enum(:find_in_batches, options) do
          total = start ? where(table[primary_key].gteq(start)).size : size
          (total - 1).div(batch_size) + 1
        end
      end

      if logger && (arel.orders.present? || arel.taken.present?)
        logger.warn("Scoped order and limit are ignored, it's forced to be batch order and batch size")
      end

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

      while records.any?
        records_size = records.size
        primary_key_offset = records.last.id
        raise "Primary key not included in the custom select clause" unless primary_key_offset

        yield records

        break if records_size < batch_size

        records = relation.where(table[primary_key].gt(primary_key_offset)).to_a
      end
    end

Defined in activerecord/lib/active_record/relation/batches.rb line 98 · View on GitHub · Improve this page · Find usages on GitHub

Defined in ActiveRecord::Batches

Signature

Options

Parameters