Some columns not read from db on EntityManager.find

Question

We are working with glassfish 2.1 and toplink-essentials 2.0.1-b09d-fcs. Our db vendor is Mysql.
Sometimes when we call em.find we get a not fully read object. It has a correctly set primerykey, version field but its properties seem to been not read from the database. They are nulls. Sometimes em.refresh is a good solution, sometimes even this is not enough and restart of glassfish only helps.
I appreciate any help... This is causing many problems as we are in production alreadt...
We cannot use a newer version of toplink-essentials because we get some problems with merging our objects then and have no resources to investigate the problem for a while.

Answer 1

Hello,
Strange problem, especially if em.refresh still won't allow you to get the data from the database - is your application using any custom options? If objects are not fully populated when they are read, it means that the cache is becoming corrupted somehow. This is common when the application does not maintain both sides of bidirectional relationships, and can also occur when an application uses stub objects for existing objects instead of reading them in. My first suggestion is to try to reproduce this in a test environment, and then isolate a particular scenario the issue occurs under - following a particular incomplete object to see how it got created and stored in the cache. Explaining the issue you have upgrading might also help determine what might be going on in the application that could cause your current issue (assuming the problems might be related, which is likely, since merge issues generally can cause cache corruptions)
In the mean time, you might try to turn off the shared cache and use an isolated cache in production to see if this helps reduce the problem.
http://weblogs.java.net/blog/guruwons/archive/2006/09/understanding_t.html describes caching in TopLink Essentials and how to turn off the shared cache in this case.
Best Regards,
Chris