Question

I am attempting to do a select on a row and update the value. While I do this I need exclusive access to the row. In other words, no other process (inside or outside the VM), should be able to read the row until after I update the row. The current value should not be “selectable”. I have tried the following transaction annotation.

@Transactional(isolation = Isolation.SERIALIZABLE, readOnly = false, propagation = Propagation.REQUIRED, rollbackFor = Exception.class, timeout=960)

This definitely works within the Spring context, but while putting a sleep statement in the middle of the transaction, I’m still able to select the current row value using a database tool.

Is there a way to get a XLOCK/ROWLOCK (whichever is the appropriate) using Spring/Hibernate?

Versions:

• Spring: 3.0.5.RELEASE
• Hibernate: 3.6.3.Final
• JTDS: 1.2.4

If I can’t use Spring/Hibernate, a link to a JTDS example would be much appreciated.

Thank you.

Answer 1

SERIALIZABLE isolation level allows other transactions to read data, but not to modify. So you need to explicitly SELECT ... FOR UPDATE (in Hibernate: Query#setLockMode(LockMode.UPGRADE)).