Re: Distributed transactions and Oracle RAC load balancing problems - advice needed!

From: Howard J. Rogers <>
Date: Wed, 06 Oct 2004 08:21:21 +1000
Message-Id: <4164708a$0$20130$>

Eirik Tryggeseth wrote:

> During deployment of an application using distributed transactions managed
> under COM+ on an Oracle 9i RAC database, we encounter situations where the
> load balancing mechanisms in the RAC result in that the component context
> in the distributed transaction (in our case two different COM components)
> cannot hold onto the same ODBC connection. Or it may be that the database
> session is changed dynamically for the ODBC connection, so that component
> 2 in the transaction cannot read updates made by component 1 in the
> transaction.
> Originally we use MS ODBC driver for Oracle (2.573.9030.00) , and Oracle
> XA
> ( We have investigated Oracle's ODBC driver (9.02.00) ,
> EasySoft's ODBC driver and DataDirect's ODBC driver to find if any of
> these can ensure that the same session is held for the connection during
> the entire lifetime of the transaction. It seems that BEA with WebLogic
> has solved the solution with their JDBC connection pool configuration
> (parameter KeepXAConnTillTXComplete).
> Has anyone else run into this problem and found a solution or work-around?
> According to Oracle's promo documents no application changes should be
> needed for using the RAC option.

My God, you didn't actually *believe* those promo documents, did you?????!

Sorry, but that's just a bit naiive.

ODBC does not failover properly in a RAC environment without a lot of handholding, at least in my (somewhat limited, admittedly) experience. Meaning that the very idea of running an ODBC app on RAC is... well, the word "brave" comes to mind.

So... good luck, basically. I hope you get the technical help you need from elsewhere on this group, but I wouldn't be holding my breath.

HJR Received on Wed Oct 06 2004 - 00:21:21 CEST

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