I've try to enable caching. The apps is using 3.2.1.ga

Consider that there are two classes

@Entity
@Cache(usage = CacheConcurrencyStrategy.READ_WRITE)
public class TrafficAlarm
{

private Set<TrafficRecord> records;

@ManyToMany(fetch=FetchType.LAZY)
public Set<TrafficRecord> getRecords() {
return records;
}
public void setRecords(Set<TrafficRecord> records) {
this.records = records;
}

}


@Entity
@Cache(usage = CacheConcurrencyStrategy.READ_WRITE)
public class FirewallTrafficRecord
{

}


Is it possible to configure the cache such that, when
em.persist(newRecord);
alarm.getRecords().add(newRecord);
the state of the "record" entities will only fetched from the second level cache, OR not ever fetched at all (as the use case shall effective trigger
a one "insert" on the association table)

I have try to use @LazyCollection, @Fetch annonation on the 'getRecords'
properties, but whatever annonation I specify, hibernate still do a join select on the association table. As the collection is very large, and worse it is also accumlating every second, I hope that it is possible to avoid select all records whenever I access the getRecords() properties.

One important is, within the application, I'll only do getRecords().add()
but never iterate the collection or even read the content within.

Another point is, in the real code, both classes are subclass only, but it shouldn't be a problem, right?

Thanks!!!

Thanks Emmanuel!

I have digg a little deeper on my problem, as I can see, enable 'cache' on the
huge collection list (property) will not solve my problem.

From the hibernate cache logging message, I can see that, whenever I update the
list
alarm.getRecords().add(newRecord);

Hibernate will lookup the list by a join on the assoc. table and the 'record' entity table.

When persists with entity manager, the cache is invalidated!!!
As a result, caching the collection does nothing.


So, now my question is now becoming two different questions, either one should help me
to overcome the performance problem I have!!

One:
Is it possible to configure hibernate such that, when it want to load the collection,
it only lookup the assocation table (DO NOT JOIN THE OTHER END OF THE RELATION),
then, use the entity id from the assocation table and lookup in the cache.


Two:
Is it LazyCollection(LazyCollectionOption.EXTRA) work on @ManyToMany relation?
If yes, does it have different behavour of 'Set' or 'List' collection.
More important, I have found some other mention that, with lazy="extra" option,
size() method of the collectio would not trigger hibernate to load the complete
collection from DB. However, how about "add()".
In my use case, the collection is huge, but my only operation is "add()".
(ie. the collection is NEVER shrink).

How to configure hibernate so that, when new element add, only 'INSERT' statement
will be issued, but not load collection and then insert.

Is there any special requirement for lazy="extra" to work?
Is it not work for owning side of the association?

1. you can achieve that with hbm files, not through annotations
2. it should work on many to many but I don't think add() has been made extra lazy. It's probably impossible for Sets, might be doable for list and bags