When you execute a passthrough SQL statement that implicitly commits or rolls back a transaction in a non-Oracle system, the transaction is affected. For example, some systems implicitly commit the transaction containing a data definition language (DDL) statement. Because Oracle Database is bypassed, Oracle Database is unaware that a transaction was committed in the non-Oracle system. Consequently, the data at the non-Oracle system can be committed, while the transaction in Oracle Database is not.
If the transaction in Oracle Database is rolled back, data inconsistencies between Oracle Database and the non-Oracle system can occur. This situation results in global data inconsistency.
Note that if the application executes a typical COMMIT statement, Oracle Database can coordinate the distributed transaction with the non-Oracle system. The statement executed with the passthrough facility is part of the distributed transaction.