I want to use another sequence (let's say my_sequence) instead of hibernate_sequence for all my objects, but I don't want to have explicitly specify my_sequence in each of those objects. Is there a way to change the default sequence (through configuration perhaps) to be my_sequence instead of hibernate_sequence?

Hibernate version:

Hiberate 3.0

provide your own id generator implementation that changes the default.

Doesn't that pose the same problem? Wouldn't I have to associate the generator with each class whose id I want to generate. I'm looking for something I can change in one place (for example, in hibernate.cfg.xml).

You will have to specify that on every class. You can do that programmatically, however, if its really such a big problem - parse the mappings, modify the DOM trees, add to configuration.

today you also specifically add "sequence" to the <generator> ...with a custom type just replace "sequence" with "org.whatever.MySequenceAsIWantIt"