Oracle RAC TAF Policy

TAF allows the DBA to configure the type and method of failover for each Oracle Net client.

TAF Policy: failover methods
1-None : Dont use TAF
2-Basic : Establish connection at failover time only
3-Pre-connect : Establish connection to both prefered instance and backup instance.

TAF Types:
1- Select : Oracle Net keeps track of all SELECT statements. tracking how many rows have
been fetched back to the client for each cursor associated with a SELECT statement.
If the connection to the instance is lost, Oracle Net establishes a connection to
another Oracle RAC node and re-executes the SELECT statements, repositioning the
cursors so the client can continue fetching rows as if nothing has happened.
The SELECT failover approach is best for data warehouse systems that perform complex
and time-consuming transactions.
2- Session: When the connection to an instance is lost, SESSION failover results only in the
establishment of a new connection to another Oracle RAC node; any work in progress is
lost. SESSION failover is ideal for online transaction processing (OLTP) systems,
where transactions are small.