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Transaction failover effectiveness

How effective ia transaction failover? If I have session-specific variables set in my session on node 1, are they maintained and accessible from node 2 if node 1 goes down? (i.e., v$session.client_info, mode, action, temp_tables, etc.)

How effective ia transaction failover? If I have session-specific variables set in my session on node 1, are they maintained and accessible from node 2 if node 1 goes down? (i.e., v$session.client_info, mode, action, temp_tables, etc.)
Transparent Application Failover (TAF) does not carry over either your session-specific variables (such as client_info, optimizer_mode, etc.) or temp tables. Basically your session is rolled back and you are reconnected to a surviving instance with the same user id that you were connected with on the failed instance.

If your system is configured for SELECT failover, a query being executed at the time of failover will be re-executed after the re-established connection with the cursor repositioned and return any remaining rows, thus providing seamless failover and a complete result set.

There are workarounds using callback functions to handle TAF limitations such as a reissue of your session variables after failover.

So, TAF is effective in re-establishing connections and completeing SELECT statements in the event of failure, but it's limitations need to be understood and accounted before implementing in a production environment.

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