Hibernate Open Session in View: Transaction per Request?

Question

I\'m using Hibernate with Spring on Tomcat. I\'ve been reading and re-reading the oft pointed to JBoss wiki page on the topic, and that has been helpful. But it leaves me

Answer 1

It is not a problem if the filter creates a session for every request, because the sessions are coming from a session pool, and they will be reused. From the view of the OS, nothing happens.

A hibernate session is, by the fact, a tcp (or socket/pipe) connection to the database server. The cost of the db conn creation is very dependent from the sql type (postgresql is notably bad in this, altough it is very good in every anything). But it doesn't means really anything, because hibernate reuses the database connections.

The simple hibernate filter solution starts a new transaction on the session for every requests, too. It is transaction from the view of the SQL: it is a "BEGIN" and "COMMIT" query. It is always costly, and this should be reduced.

IMHO a possible solution were, if the transactions were started only at the first query of the current request. Maybe spring has something usable for this.