Method: EachBatch::BatchEnumerator#each

Defined in:
lib/each_batch/batch_enumerator.rb

#each ⇒ Object 



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# File 'lib/each_batch/batch_enumerator.rb', line 41

def each
  return self unless block_given?

  batch_relation = relation.reorder(keys.product([order]).to_h).limit(batch_size)
  batch_relation.skip_query_cache! # Retaining the results in the query cache would undermine the point of batching

  yielded_relation = batch_relation
  op = order.to_s.casecmp('desc').zero? ? :lt : :gt
  pk = relation.primary_key.to_sym

  loop do
    # consistent with rails load behavior.
    if @load
      records = yielded_relation.records
      yielded_relation = relation.where(pk => records.map(&pk))
      yielded_relation.send(:load_records, records)
    end

    yield yielded_relation

    offsets =
      if @load || yielded_relation.loaded?
        break if yielded_relation.length < batch_size

        yielded_relation.last.attributes_before_type_cast&.values_at(*keys)
      else
        # we need an additional query to fetch the last key set
        offsets = yielded_relation.offset(batch_size - 1).limit(1).pluck(*keys).first

        break if offsets.nil?

        Array.wrap(offsets)
      end

    yielded_relation = batch_relation.where_row(*keys).public_send(op, *offsets)
  end
end