In one of the postings joe( weblogic support person ) wrote something that
to me SEEMED to imply that if you start a tx and are using opimistic
concurrency then then the db takes care of comparing all tables touched and
changed in your tx and does a roll back if your official copy is not same.
I.e it goes through a 2 phase commit locking the official copies of tables
and updating them. I am assuming the db will take care of it without me
having to have a timestamp column.
Joe said: "Optimistic locking is where every datum is copied to a
client-private
space in the DBMS on access, and updated or referred to there as needed,
with no lock on the official copy and no interfering with other DBMS
transactions. At commit time, each datum-copy is checked against the
official
version, and if the official version has not changed during the transaction,
all is well and the modifications are made official. If some official datum
has changed because of some other transaction since this transaction
started,
the whole transaction is failed, and rolled back. The value of this style
is that multiuser access is maximized, and things go fast. The cost is that
large transactions may need to be entirely redone more frequently than
if a conservative locking scheme were employed."
This is just my interpretation of what I read. What do you think ?
> -----Original Message-----
> From: A mailing list for Enterprise JavaBeans development
> [mailto:[EMAIL PROTECTED]]On Behalf Of Andrew J. Roehr
> Sent: Wednesday, March 03, 1999 2:04 PM
> To: [EMAIL PROTECTED]
> Subject: Re: Entity Bean Management
>
>
> Sachin, I think you are mistaken. generally, you ahve to set a column in
> the table as type "timestamp" and sleect it back into your instance. When
> you do the update, the DB's usually look at and compare these values. If
> the TS has changed on the DB, then an error gets thrown whih you can trap
> and deal with programatically. In the absence of this kind of error
> management, you will simply over write what is there.
>
> BTW, another issue for you to consider is "what happens if
> someone deletes a
> record behind me". A business process needs to be identified for these
> conditions.
>
> Andrew J. Roehr
>
> Chief Technology Officer
> Agillion Inc.
> http://www.agillion.com
>
> 7600-B N. Capital of Texas Highway
> Suite 220
> Austin, TX. 78731
>
> (w) (512) 682-8002
> (f) (512) 306-7331
>
> [EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>
> [EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>
> [EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>
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