Currently we are running Tomcat 5.5 as a servlet container, so there is no TransactionManager. We are also using JBoss Tree Cache (localy with no clustering) for our 2nd level cache.

I understand that since we don't have a TransactionManager our level 2 cache will not be transactional with the database. I do not really understand what or how this will effect our environment since it is a local cache and not a clustered environment.

If someone could shed some light on this, that would be great. For example if there could be any negative effects...

Thanks in advance!

Basically, you have two transactional resources particpating in the same logical transaction (the database and the cache). Without the transaction manager, it is possible for these two to become out of synch if "something goes wrong".

Say for example, you ask Hibernate to flush the dirty state of an entity. So, it needs to write an entry into the cache (for the state change) and update a row into the db. So say the put into the cache works fine and then the database operation fails. Well, now the cache has consistency issues; the next time you try to read that entity, you will get back the "updated entity" even though that updated state was not successfully written to the database.

This all assumes use of the "transactional" cache strategy...

Thanks for the reply.

It all makes sense now!

Do you need more points or should I save them for someone in need?