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From Brian McCallister <mccallis...@forthillcompany.com>
Subject Re: OTM + Connections/Transactions
Date Wed, 24 Sep 2003 17:53:27 GMT

On Wednesday, September 24, 2003, at 01:09 PM, Raghuram Rajah wrote:

> Hi Brian,
> How do multiple connections help there? Without a 2PC to co-ordinate 
> the
> two-connections you would just merely end up with non-ACID 
> transactions.

The specific situation I need is a long transaction in the duration 
sense more than the multiple database (though that exists too). It 
holds to a lesser degree in the multiple database sense as well -- if 
you can trust that atomicity is maintained in the application level 
transaction. You lose atomicity at the database level, but if you can 
guarantee the only thing touching the databases is a single OJB 
instance, you can maintain atomicity in practice. That said, I am more 
concerned with the time sense long transaction - potentially hours.

It is *incredibly* convenient for me to be able to start a transaction 
and make some changes, hold onto said transaction, make changes to 
things in the context of the transaction, remove things that only exist 
in the context of the transaction, etc. There are multiple (dozens) of 
round trips to the user during this process. Holding onto a single DB 
connection the entire time is not an option, but the changes all need 
to be made within one logical transaction.

Versioned tables in Oracle allow this type of behavior, but they are 
VERY Oracle specific, which is a pita. If we can encapsulate all of the 
changes at the object level and can then commit this back to the 
database(s) in a single (optimistic -- while there are many users, they 
work on different data in the database for the most part) transaction 
life is much happier. It is theoretically very memory intensive, but 
memory is far less expensive than Oracle licenses (and versioned tables 
are not very performant anyway).

My understanding of the OTM is that it should allow this behavior. It 
is very powerful.


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