Previously, only transactions in a PREPARED state were allowed to be rolled back administratively. That is, if a session that was part of a distributed transaction did not terminate gracefully, the transaction remained in a state that could not be cleaned up by an administrator. In Message Queue 4.1, you can now use the Command utility (imqcmd) to clean up (roll back) transactions that are in the following states: STARTED, FAILED, INCOMPLETE, COMPLETE, and PREPARED.
To help you determine whether a particular transaction can be rolled back (especially when it is not in a PREPARED state), the Command utility provides additional data as part of theimqcmd query txn output: it provides the connection id for the connection that started the transaction and specifies the time when the transaction was created. Using this information, an administrator can decide whether the transaction needs to be rolled back. In general, the administrator should avoid rolling back a transaction prematurely.