For global transactions, each participating group has its own transaction branch, and a distinguished transaction branch identifier (XID) identifies each branch. If a global transaction involves multiple groups, Tuxedo adopts two-phase commit on each branch, taking the first participating group as the coordinator.

With the common XID (transaction branch identifier) feature in Oracle Tuxedo Advanced Performance Pack, Tuxedo shares the XID of the coordinator group with all other groups within the same global transaction. If a transaction involves multiple RAC databases or resource managers, then separate branches will be utilized to manage the involved resources. This ensures efficient and effective management of the transaction across multiple systems. This is as opposed to each group having its own XID and thus requiring two-phase commit in earlier releases if multiple groups are participating.

Common XID eliminates the need to XA commit operations for groups that connect to the same Oracle RAC instance through the same service by using the coordinator branch directly.

In the cases where all groups in a global transaction use the coordinator branch directly, one-phase commit protocol (instead of two-phase commit protocol) is used, and thus avoids writing TLOG.

For more information about configuration, see Introduction to Using Oracle Tuxedo Advanced Performance Pack.