I am working on a simple example to illustrate my problem. It consists of two entities, (Contact and PhoneNumber) with a one-to-many relationship between them.

Contact -> PhoneNumbers

My application queries a set of contacts and their corresponding phone number using a set of complex queries. Once these have been retrieved I am going some further processing and navigate the relationship using phoneNumber.getContact quite a bit. The initial call to query all contacts and all phone numbers is done using:



I would have expected that the getContact call on PhoneNumber or getPhoneNumbers on Contacts would not result in further queries being executed against the database, however during profiling I found that it was queried again. This was killing the performance of my application. During my investigation I first tried to access the phone number from a constructed HashTable based on my previous result. However since PhoneNumber does not expose the Contact's primary key this didn't work.

My first question is : Is there a way to access the foreign key on the PhoneNumber table without reading the contact. This would allow me to access the contact in my own internal cache.

Then I read up on the cacheing options available and figured I give this a try. I added the following to persistence.xml


as well as created ehcache.xml in my classpath:


However this did not improve my problem at all. Maybe I am missing something, or maybe this is not the way it is supposed to work. Any suggestions on how I can avoid the second query to the database to fetch the Contacts I already fetched previously. I am doing both queries in the same transaction.

I am using the following versions:
Hibernate Annotations 3.4.0.GA
Hibernate 3.3.2.GA
Hibernate Commons Annotations 3.1.0.GA
Hibernate EntityManager 3.4.0.GA

Thanks in advance
Alex

After I added the following to the persistence.xml file I hoped it would fix the issue:



However from the hibernate debug log it doesn't seem to work.


After have a careful look at the debug log I cannot find any reference to the contacts (ID=7AEDD518-8386-41B9-A2F5-ECDB8D26FA31) every having been cached, even though before adding this new line to the persistence.xml file this contact was definitely listed and cached. Also the queries for the contact's phone number still hit the database as the cache is being missed.

After some further tests is seems that the contact was indeed cached, but the debug log file was overwritten. So the contact is cached, the phone numbers are cached, and the contact.getPhoneNumbers are cached, however they all seem to be cached independently of each other. Is there an option to combine contact.getPhoneNumbers and PhoneNumbers and similarly phoneNumber.getContact and Contacts into a single unified cache ?

During another test the log reported the following. The Contact was cached:



and shortly thereafter the related phone number was cached as well


However a little later in the process it couldn't find the phone number linked to that contact:


It seems that com.demo.Contact.phoneNumbers#C72A3275-F04C-4446-8A42-FE474F1F06C9 are not treated as the same as com.demo.PhoneNumber#5BAE41F4-20E9-47E0-824F-0AA9887523E5 even though they refer to the same object.