Using the 2PC Protocol
Two-Phase Commit (2PC) is an IMS and CICS protocol for committing update transactions
processed by multiple systems that do not share the same locking and recovery mechanism.
For detailed information on 2PC, see Teradata Director Program Reference.
Consider the following disadvantages of using the 2PC protocol:
Performance may decrease because, at the point of synchronization, up to two additional
messages are exchanged between the coordinator and participant, in addition to the
normal messages that update the database
If your original SQL request took longer to complete than your other requests, the
performance impact due to the 2PC overhead will be less noticeable.
• If Teradata Database restarts, and a session using the 2PC protocol ends up in an
IN-DOUBT state, Teradata Database holds data locks indefinitely until you resolve
the IN-DOUBT session. During this time, other work could be blocked if it accesses
the same data for which Teradata Database holds those locks.
To resolve this situation, perform the following steps:
Use the COMMIT/ROLLBACK command to resolve manually the IN-DOUBT sessions.
Use the RELEASE LOCKS command.
Use the RESTART command to restart your system.
2PC causes no system overhead when it is disabled.