Two-phase Commit and Recovery

The two-phase commit protocol is used to ensure to ensure that distributed queries are uniformly committed or rolled back across multiple database servers. A database server automatically uses the two-phase commit protocol for any transaction that modifies data on multiple database servers.

Since Extended Parallel Server does not support remote updates, multi-site updates within a single transaction are not possible. Therefore, the two-phase commit protocol does not apply to queries originating on Extended Parallel Server. In this case, distributed transactions are treated the same as local transactions and are rolled-back or committed depending upon the point the failure occurs. Any statement that would require the use of the two-phase commit protocol is aborted and an error message returned.

For more information, see the chapter on multi-phase commit protocols in the IBM Informix Dynamic Server Administrator's Guide.