Two-Phase Commit Ensures Distributed Transaction Consistency

The Two-Phase Commit (2PC) protocol is an algorithm designed in the fields of computer networking and databases to ensure consistency across all nodes of a distributed database during transaction commits.

Summary of the Two-Phase Commit Protocol:
Participants notify the transaction manager of the success or failure results of their operations. The transaction manager then decides whether each participant should commit or abort based on feedback from all participants.

• Prepare Phase: The transaction manager sends prepare messages to all resource managers. Each resource manager either directly returns a failure or, if successful, writes local redo and undo logs to the disk without committing them.
• Commit Phase: If the transaction manager receives failure messages from any participant or experiences a timeout, it sends rollback messages to all resource managers; otherwise, it sends commit messages. Resource managers execute the commit or rollback operations based on the coordinator's instructions and release locks held throughout the transaction processing.