Guys, How difficult would be to support transactional tasks?
What means every job in task executed in it's own transaction. In case of single job failure or reduce phase failure all transaction started by jobs are rolled back. Only if all jobs are successfully executed, corresponding transactions are commited. Also it would be very desirable to implement tasks failover in the similar way how jobs failover is implemented. In case of master's failure jobs are rolled back, and task is restarted on another node. This should greatly simplify implementing complex business processes. -- Best regards, Alexei Scherbakov