# File vapor/transaction.rb, line 38
    def begin
      unless @active 
        @datastore.begin_transaction
        unless @persistence_manager.autocommit_in_progress?
          @persistence_manager.autocommit = false
        end
        @log = TransactionLog.new
        @log.committer = @committer
        @active = true
      else
        raise NestedTransactionError
      end
    end