Duplicate processing by DBAdapter when using Distributed Polling with Logical Delete Strategy

Question

We have DBAdapter based polling services in OSB running across two Active-Active clusters (total 20 managed service across 2 clusters),
listening to the same database table. (Both clusters read from the same source DB). We want to ensure distributed polling without duplication,
hence in the DBAdapter we have selected Distributed Polling option, meaning we are using "Select For Update Skip Locking".
But we see that sometimes, same rows are processed by two different nodes and transactions are processed twice.
How do we ensure that only one managed server processes a particular row using select for update? We do not want to use the markReservedValue option which was preferred in older version of DBAdapter.
We are using following values in DB Adapter configuration, the Jdev project for DBAdapter and the OSB proxy using DBAdapter are attached.
LogicalDeletePolling Strategy
MarkReadValue = Processed
MarkUnreadValue = Initiate
MarkReservedValue = <empty as we are using Skip Locking>
PollingFrequency = 1 second
maxRaiseSize = 1
MaxTransactionSize = 10
DistributionPolling = checked   (adds lock-n-wait in properties file and changes the SQL to SELECT FOR UPDATE SKIP LOCKED)
Thanks and Regards

Answer 1

Hi All,
Actually I'm also facing the same problem.
Step I follwed:
1) Created a job_table in database
create talbe job_table(id, job_name, job_desc, job_status)
2)created a bpel process to test the Inbound distributed polling.
3)Configure the DBAdapter for polling.
a)update a field in the job_table with logical delete.
b)select the field name form the drop down
c) change the read value-->Inprogress and unRead value--->Ready
d) dont change the value for Reserved value
e) select the check box for "distributed polling".
f) the query will be appended with "For update NoWait."
g)click next and then finish.
4) Then i followed the below steps.
To enable pessimistic locking, run through the wizard once to create an inbound polling query. In the Applications Navigator window, expand Application Sources, then TopLink, and click TopLink Mappings. In the Structure window, click the table name. In Diagram View, click the following tabs: TopLink Mappings, Queries, Named Queries, Options; then the Advanced… button, and then Pessimistic Locking and Acquire Locks. You see the message, "Set Refresh Identity Map Results?" If a query uses pessimistic locking, it must refresh the identity map results. Click OK when you see the message, "Would you like us to set Refresh Identity Map Results and Refresh Remote Identity Map Results to true?Ó Run the wizard again to regenerate everything. In the new toplink_mappings.xml file, you see something like this for the query: <lock-mode>1</lock-mode>.
5) lock-mose is not changed to 1 in toplink_mappingss.xml
Can we edit the toplink_mappings.xml manually.
If yes, what allt he values Ineed to change in toplink_mappings.xml file, so that it will not pick the same record for the multiple times in clustered environment.
Please help me out this is urgent.
Thanking you in advance.