Draft benchmark code for testing speed of db records updating with commit transaction per each record, and without it

test.rb

# $ rails c
# > require "#{Rails.root}/test.rb"
# > TestTb.new.test1; TestTb.new.test2
# * Results: 27252 records processed in: 56 sec (within Transaction), 107 sec (without Transaction)

class TestTb
  TRANSACTION_SCOPE = -> (func) { Book.transaction { func.call } }
  WHERE_QUERY = -> { { autor_id: @value == 0 ? 1 : 0 } }

  def initialize; @percent_count = @percents = @count = 0 end
  def test1; p 'Single transaction'; call_transactionable(true, 0) end
  def test2; p 'Multiple transactions'; call_transactionable(false, 1) end

  private

  def call_transactionable(transactionable, val)
    @value = val
    with_init { transactionable ? TRANSACTION_SCOPE.call(self.method(:do_update)) : do_update }
  end

  def with_init
    puts "count = #{@count = Book.where(instance_exec &WHERE_QUERY).count}"
    ActiveRecord::Base.logger.silence { puts Benchmark.ms { yield } }
  end

  def do_update
    Book.where(instance_exec &WHERE_QUERY).find_each { |book| update_and_log book }
  end

  def update_and_log(mv)
    mv.update(autor_id: @value)
    @percent_count += 1
    return if @count/100 != @percent_count
    print "\r #{@percents}%"
    @percents += 1
    @percent_count = 1
  end
end