Automatic resubmission of queries
TAF can automatically resubmit queries that were active at the time the first
instance failed and can resume sending results back to the client. Oracle will
reexecute the query as of the time the original query started. Oracle??™s read consistency
will therefore provide the correct answer regardless of any activity since
the query began. However, when the user requests the ???next??? row from a query,
Oracle will have to process through all rows from the start of the query until the
requested row, which may result in a performance lag.
Callback functions
Oracle8i enhanced TAF by enabling the application developer to register a ???callback
function??? with TAF. Once TAF has successfully reconnected the client to
the alternate instance, the registered function will be called automatically. The
application developer can use the callback function to reinitialize various aspects
of session state as desired.
Failover-aware applications
Application developers can leverage TAF by writing ???failover-aware??? applications
that resubmit transactions that were lost when the client??™s primary instance
failed, further reducing the impact of failure.
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