One may receive ORA-25408: can not safely replay call when using failover. This will depend on the failover type and on what you are executing.
AF only works for idle sessions and SELECT statements. The following operations will give an error (user program must restart the operation after fail-over):
* PL/SQL program units - stored procedures, functions, packages * DML - INSERT, UPDATE, DELETE, SELECT ... FOR UPDATE * DDL - CREATE, ALTER, DROP, TRUNCATE, GRANT, REVOKE, etc.
For example if you are doing an insert and the database goes down and failover occurs, "ORA-25408 can not safely replay call" is expected and the application should handle this exception and re-execute the insert.
If you are in a transaction and failover occurs you will also receive an error message and you have to handle this and issue a rollback.
In case you have configured failover to be of type SESSION, you will not able able to recover your selects either and you will need to replay them.