Hi,
I am running a web application which uses hibernate for persistance of the data.
When i make some changes to the database manually, it doesn't reflect in the hibernate cache. I mean when i fetch a set from a class, it gives size zero. Can anyone please help me figuring this out.
Is there any way to expire the hibernate cache manually and ask it to recache everything from the database.

Yes. This is all in the caching chapter of the manual. Look for Session.evict() and SessionFactory.evict(). You can also configure your cache provider to expire information after some timeout, this way you don't have to "manually" manage your caches.

-Chris