I'm using Hibernate with 2nd level cache using Ehcache. I found that if the result returned from session.get() (searching by primary key) is NULL, the value will not be cached in both 1st level and 2nd level cache and SQL will be fired to database again. There is no problem if the value returned is not null for the same entity.

I have debug using the hibernate and ehcache source and I'm sure that the cache is enabled and called properly. Here are my findings of the problem:
In the EntityLoader(Loader).initializeEntitiesAndCollections method, if there is no result returned from database, the hydratedObjects is empty. So the method TwoPhaseLoad.initializeEntity (which will put the result into the cache) will never be called.





Actually the null value is expected to be cached also as the same criteria will always return null, no matter how many times I called to database.

I have browser all hibernate and ehcache documentation and forum and no related config is available. Ehcache ifself support null value for caching. There is also no documentation saying that null value from session.get() cannot be cached. Actually, I have post to JIRA Issue tracking system but is rejected with unknown reason.
http://opensource.atlassian.com/project ... e/HHH-3522

In our system, we will redirect the request to other system based the existence of customerId in our system. So, if NULL value cannot be cached, there will be a large number of redundant SQLs fired to database which will greatly affect our performance.

Do anyone have solution for this situation? Thanks all for your help!

Hibernate version:
3.2.5
Mapping documents:
N/A
Full stack trace of debug that comes to point of failure:



Name and version of the database you are using:
Oracle10g[/code]

My understanding is that the second level cache is just a cache of objects so I would expect this behaviour. What you're describing is a query cache, i.e. to remember that the result of querying for an object by its ID returned null.

So instead of doing a get(id) use an explicit query to find the object by its ID and set the cacheable flag on that query:

Thanks for your reply.

But how about the first level cache? I would expect the NULL value would be cached in first level cache if I'm calling session.get(id). But from my debug, it will not be cached in first level cache also. Do I misuse the session.get(id) or any configuration needed?

Actually, I am not doing a query cache. I'm using session.get(id) to get the object by primary key. And I think hibernate would then cache the result in first level cache even there is no second level cache enabled. Hope that my understanding is correct.