What happens if I rollback a transaction after I flush ? Does it roll back ?

My Problem is that I have a batch update process through my web app. And during that process I have to do session.flush() and session.clear() frequently. However the server sometimes crashes.

And I want to ensure that if server crashes the entire batch process is rolled back. How can I do it ?

Transaction life is something like:

begin()
flush()
flush()
...
commit or rollback

flush is a write from memory to database (in this case), but if database transaction is started (and mostly hibernate transaction ~ db transaction) it can be still rollbacked, or commited.

clear() will clean the session cache, be sure you call the flush before it or you will loose your changes.

For example, you can see the usage of frequent flush, clear here:
http://www.hibernate.org/hib_docs/v3/re ... batch.html

Regards,
Pavol