Re: Optimistic locking question

[Larry Meadors]

I think that is most likely your best bet.

Larry

On 3/15/06, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:

I would agree that this would be an easy implementation that I would prefer. The problem is that I am working with an existing Data Model that I inherited and I cannot change without having an enormous impact on multiple groups and application UI's. (Not something that I am ready to propose)  This is the model that I am stuck with unfortunately.

I think I have a solution to the problem but I feel that it is a very dirty one. I could define an additional field in each domain object and call it 'now', which would get the current timestamp, set by the Dao, just prior to performing the insert. I would then update the value in the SQL as follows:

   update customer set
    name = #name#,

    record_date = #now#,

    ...
  where
    id = #id#
  and
    record_date = #recordDate#    

Then if the update was successful I could have the Dao update the record date with the value of now. It's dirty, so I am in hopes that someone has a better solution for me.

Thanks...

Chris Mathrusse
[EMAIL PROTECTED]
Sybase, Inc
One Sybase Drive
Dublin, CA 94568
(925) 236-5553

"MCCORMICK, Paul" <[EMAIL PROTECTED]> 03/15/2006 05:30 PM Please respond to user-java@ibatis.apache.org

To < user-java@ibatis.apache.org> cc Subject RE: Optimistic locking question

Instead of using a timestamp I use an integer and increment the value on every update.
 
update customer
set NAME= #name#,
    VERSION_ID = VERSION_ID + 1  
where ID = #ID# and VERSION_ID  = #VERSION_ID#
 
Then in the Dao I would increment versionId value on the CustomerDTO object if the update succeeded.
        int rowCount = getSqlMapClientTemplate().update( "Customer-update", record);
       
       if(rowCount == 0) {
           throw new OptimisticLockingFailureException("Optimistic Lock Failure! Unable to update record: " + record);            
       }
        record.setVersionId(record.getVersionId() + 1 );

---

From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]
Sent: Wednesday, 15 March 2006 11:55 PM
To: user-java@ibatis.apache.org
Subject: Optimistic locking question


I have a table:

CREATE TABLE CUSTOMER
       ID NUMBER NOT NULL,
       NAME VARCHAR(32) NOT NULL,
       RECORD_DATE TIMESTAMP NOT NULL,
       ...

The Record_Date is used to determine the last time the record was updated, so when I perform an update my SQL would look something like:

  update customer set
    name = #name#,
    record_date = getDate(),
    ...
  where
    id = #id#
  and
    record_date = #recordDate#    

This allows me to do the following in my Dao:
       
       int rowCount = getSqlMapClientTemplate().update( "Customer-update", record);
       
       if(rowCount == 0) {
           throw new OptimisticLockingFailureException("Optimistic Lock Failure! Unable to update record: " + record);            
       }
       
       return rowCount;        


The problem that I have is if my SQL is performing the update of the record_date field when the insert is performed, how do I update my domain object with the new value without performing a read from the table?


Thanks for the help...

Chris Mathrusse
[EMAIL PROTECTED]
Sybase, Inc
One Sybase Drive
Dublin, CA 94568
(925) 236-5553

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