So what Sanne wanted to say is that the query plan cache is not using Ehcache.

You blurred the queries so I have one small question about that: do they contain parameter values? (I don't think you would blur table names). In this case, you should use parameters and have only one query with parameters, thus avoiding storing a plan per parameter value. But maybe you were just being cautious .

Just asking but would you share your hprof file privately with us so that we can have a look? Obviously this should be done only if it does not contain highly sensitive information.