Hi Gail,

Thanks for you reply. Our Websphere specialist tells me that we currently cannot upgrade Hibernate because of dependency on javaassist library of both Websphere 8.5.5 and Hibernate. According to him, versions of Hibernate > 4.2.7 use a, newer version than Websphere, which is incompatible. Is this something known to you? You know a way to solve this? (Other than move to Websphere 9)

Apart from upgrading, I looked at the source code in the involved classes and I don't see any code changes concerning the cache key handling with custom types between 4.2.7 and newest. It is clear from the source code that the problem is still there. Maybe you can have a look as described above? You agree?

Then I come back to my question "Doesn't the query string alone already uniquely identify the query plan?". Just using the query string as key would make things much easier and better performing and solve this issue right away.