Re: TAF and FCF together ?

vissuyk_at_yahoo.com wrote:
> Hi All,
>
> I am desperately trying to find answers on how to use these two
> technologies togther. As per Oracle docs, I cant use them together -
> unless I am misreading it.
>
> Could anyone suggest how I might accomplish these two together in my
> application. I can use thin or thick application.
>
> With thick we can get TAF. With thin we can get FCF (fast connection
> failover).
>
> Thanks
>
> Vissu

What you are reading is true. The two are mutually exclusive. If your application is only read-only with respect to the DBMS, then TAF can work out, but if you're doing anything more serious, it can't actually guarantee that everything will work or be transparent during a failover.
If I remember when I get to work, I'll post the oracle document that describes all the possible ways that TAF might fail to make failovers transparent.

   If you're doing clientside Java, TAF can actually leave the connection
in a worse than dead state, where the basic connection can continue to do plain new queries, but any PreparedStatements you already had may be dead, and any query you may have been processing may fail or return partial/incorrect results. Any XA transaction will have to be rolled back and redone anyway, any DBMS session state you've changed will be lost, etc.
  All in all, it's much more reliable if you're writing to the DBMS or doing
transactions etc, is to be able to handle a connection failure by closing
the dead connection, asking for a new one (which will work with FCF or some other middleware-based failover schemes), and redo your current tx.

Joe Weinstein at BEA Systems Received on Thu Sep 14 2006 - 09:28:01 CDT