I have an application where multiple instances (of the application) are creating data that eventually need to be merged together. I was wondering if the uuid.hex generated id can be considered globally unique? The application runs in disconnected machines so the machine's IP address will not be unique for each machine in it disconnected state. Unless, uuid.hex also works with host name which is unique for each machine.

If uuid.hex will not get me the global uniqueness that I am looking for, how can I plug my own uuid generator in hibernate? Can someone provide and example?

Thanks...

It can be considered as unique if:
- you don't start your JVM in the same quarter of second
- OR you don't generate unique ID in the same millisecond (minus your JVM precision in currentTimeMillis)

This is probably the best you can do wo using jni or reading a different seed for each JVM instance.

If you want to do your own,
Have a look at :
- section 5.1.4.1
- the source code of hibernate in net.sf.hibernate.id (and the UUIDGenerator class).

It's pretty simple.

correct



which would be very difficult to guarantee

- OR you are on a single network, so you can guarantee that IP adresses are unique