TMF Introduction (G06.26+)

Transaction Coordination
HP NonStop TMF Introduction—522414-002
2-13
Summary of Transaction Coordination
Stage
1
The application issues a request to begin a transaction, thereby creating a
new TMF transaction. The transaction is originated and identified as an
active recoverable unit. Transaction identifiers are transmitted among
processes that do the work of the transaction.
Stage
2
The transaction modifies the database by reading, changing, deleting, and
inserting rows (records). TMF maintains locks on all data that the
transaction inserts, deletes, or changes. Concurrently, TMF builds an audit
trail of all database modifications.
Stage
3
The application issues the request to commit the transaction, indicating
that changes should be permanent. TMF ensures that all changes to the
database are recorded in the audit trail so they can be used for any
subsequent recovery operations. As the operations for the two-phase
commit protocol complete, all locks on the affected data are also released.