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.
Performance Impact
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.
- If your original SQL request took longer to complete than your other requests, the performance impact due to the 2PC overhead is less noticeable.
- If the database restarts, and a session using the 2PC protocol ends up in an IN-DOUBT state, the database holds data locks indefinitely until you resolve the IN-DOUBT session. During this time, work that accesses the same data for which the database holds those locks may be blocked.
To resolve this situation, perform the following :
- 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.
W2PC causes no system overhead when disabled.
Related Information
See Teradata® Director Program Reference, B035-2416.