Distributed Polling Not working for Sybase Database poller Proxy

Question

I am using a Proxy service which is polling records from a sybase database. When I tried to deploy this proxy in a clustered environment I noticed sometimes it is polling the same record twice. So I tried to enable distributed polling in my proxy by adding *<lock-mode>lock-no-wait</lock-mode>* in my topplink_mapping.xml file. But activating this change resulted error in the log file stating "Incorrect syntax near 'NOWAIT'".
Later on I found out that it is a known issue ...for reference check [http://www.oracle.com/technetwork/middleware/docs/aiasoarelnotesps5-1455925.html|http://www.oracle.com/technetwork/middleware/docs/aiasoarelnotesps5-1455925.html] with bug # 13405718.
So I am stuck here...and no solution yet.
Any suggestion??

Answer 1

You can Emulate AQ functionality for any Non-Oracle Database where sometimes the *Clustered DB-Adapter[Poller]* polls the same record more than once.
Say, you need to poll 'status' column of table 'A' for a status 'POLL_IT'
1. Create a Table 'DUMMY_AQ' matching required column signatures from table 'A'
2. Create a Trigger on table 'A' for copying the row content on Insert or Update for status 'POLL_IT' in to 'DUMMY_AQ' table;
3. Poll DUMMY_AQ with Row Level Read lock & Delete On Read , that way it will is ensured that so that only One Instance of your Clustered DB Adapter can have visibility to any newly inserted row having status 'POLL_IT' .