Two-phase commit ensures that distributed transactions (that is, transactions involving multiple databases) occur consistently across all databases. Two-phase commit is not necessary for transactions involving a single database.

For detailed information on two-phase commit, see Distributed Transaction Processing.

Note: If you use two-phase commit, you should also use after-imaging to ensure database integrity and avoid backup synchronization problems. Although two-phase commit ensures that two databases remain synchronized, it does not protect you from a lost database or BI file. If you lose an entire file or disk, you must use the AI file to roll forward to the point of the crash.