Postdecision phase

During the postdecision phase, the coordinator and participants perform the following dialog:
Coordinator
The coordinator writes the commit record or rollback record to the coordinator's logical log and then directs each participant database server to either commit or roll back the transaction.
Participants
If the coordinator issued a commit message, the participants commit the transaction by writing the commit record to the logical log and then sending a message to the coordinator acknowledging that the transaction was committed. If the coordinator issued a rollback message, the participants roll back the transaction but do not send an acknowledgment to the coordinator.
Coordinator
If the coordinator issued a message to commit the transaction, it waits to receive acknowledgment from each participant before it ends the global transaction. If the coordinator issued a message to roll back the transaction, it does not wait for acknowledgments from the participants.