Is it expensive to retrieve or would creating copies of it also too expensive? If not, will using JPA be a solution? Most of the JPA providers cache retrieved instances in the global cache (check their documentation for the setting that would work for you), so the only penalty that you'd encounter would be creating a copy when you call em.find() (don't use queries though) to get a hold of it when you need it.
Regards,
-marina
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