Hi
Nested Transactions applies to JDBC more than to Hibernate Session. So which version of JDBC that you are using matters for this nested transactions.
In JDBC 3.0, the transaction manager supports nested transactions via JDBC 3.0 Savepoints. The "nestedTransactionAllowed" flag defaults to false, though, as nested transactions will just apply to the JDBC Connection, not to the Hibernate Session and its cached objects. You can manually set the flag to true if you want to use nested transactions for JDBC access code that participates in Hibernate transactions (provided that your JDBC driver supports Savepoints).
for more visit the link.
http://www.springframework.org/docs/api ... nager.html