The distributed database consists of a collection of data with different parts under the control of separate DBMS, running an independent computer system.
A distributed transaction includes one or more statements that, individually or as a group, update data on two or more distinct nodes of a distributed database.
Two-phase commit (2PC).
With a two-phase commit protocol, the distributed transaction manager employs a coordinator to manage the individual resource managers.
Prepare phase: Each participating resource manager coordinates local operations and forces all log records out: If successful, respond "OK". If unsuccessful, either allow a time-out or respond "OOPS"
Commit phase: If all participants respond "OK": Coordinator instructs participating resource managers to "COMMIT". Participants complete operation writing the log record for the commit. Otherwise: Coordinator instructs participating resource
managers to "ROLLBACK". Participants complete their respective local undos.