Re: TAF and FCF together ?

Hi Joe,

These are very good questions that anyone contemplating TAF should
investigate..
I have discussed some of these in my book (chapter 7) and fairness
towards those who bought it suggests that i only give the following
summary:
a) things that TAF does well (transparently): connection failover and
query resubmit (or query failover) - with performance penalty
b) things that TAF does not do well (not transparent or does not work
at all): rolling back active transaction, and failing over session
states

As of 10g R2, FCF is bound to RAC while TAF may be used to failover
single-instance sites (Data Guard); TAF may also be customized through
its callback interface.

Hope this helps, Kuassi

joeNOSPAM@xxxxxxx wrote:
Hi Kuassi, could you discuss the ramifications of these
TAF considerations as it relates to JDBC?

(metalink registration required)
http://metalink.oracle.com/metalink/plsql/ml2_documents.showDocument?p_database_id=NOT&p_id=97926.1

Under what conditions would a running JDBC application
suffer from "Continuing work on existing cursors may raise an error
(eg: ORA-25401 "cannot continue fetches")"? Will existing
PreparedStatements
ever become defunct?

When will JDBC queries fail with "Failed over selects may raise an
error"
and what error?

Do JDBC connections ever rely on having altered the session state with
such calls as "ALTER SESSION SET NLS_DATE_FORMAT='YYYY-MM-DD';"
or global temp tables, which will be lost on failover?

If a JDBC client is using the Oracle OCI driver, doing transactions,
how/when
to they know that a failover occurred so they know to roll back?

thanks,
Joe

.

Relevant Pages

  • Re: TAF and FCF together ?
    ... *not* survive failover, whether with a delay or not. ... TAF will not always successfully restart a query in progress. ... especially for JDBC in a complex working environment. ... when the application makes it's next use of the connection. ...
    (comp.databases.oracle.server)
  • Re: TAF and FCF together ?
    ... *not* survive failover, whether with a delay or not. ... TAF will not always successfully restart a query in progress. ... especially for JDBC in a complex working environment. ... when the application makes it's next use of the connection. ...
    (comp.databases.oracle.server)
  • Re: TAF and FCF together ?
    ... *not* survive failover, whether with a delay or not. ... TAF will not always successfully restart a query in progress. ... JDBC is just a conduit b/w the RDBMS and TAF. ... The surviving PreparedStatement assumes that the Statement handle's ...
    (comp.databases.oracle.server)
  • Re: TAF and FCF together ?
    ... a programmer needs to do to make TAF and the Oracle ... *not* survive failover, whether with a delay or not. ... of rows as had been fetched by the previous cursor. ... TAF considerations as it relates to JDBC? ...
    (comp.databases.oracle.server)
  • Re: TAF and FCF together ?
    ... *not* survive failover, whether with a delay or not. ... TAF will not always successfully restart a query in progress. ... JDBC is just a conduit b/w the RDBMS and TAF. ... PreparedStatement and their cursor are ...
    (comp.databases.oracle.server)