Is there a database independent solution for generating Id's for a table without changing the domain object when passing from one db to another ?

It works the solution with generator-class="native" ?

For the db's that uses sequences, the sequences will be created automatically ?

native is the solution you're looking for. But the sequence is not created automatically - I guess (haven't tried it yet, but this is the only way that makes sense) you must provide the sequence parameter:

The parameter is only used if the database actually supports sequences.

Erik

As I understand from Hibernate documentation, if I set generator-class="native" it will pick for each db the "native" solution for generating id's, and for Oracle db for example it will pick "sequence".
If the sequences are not automatically created and you have to provide their name this is not an db independent solution.

I do not really agree with you. It actually depends what your expect when you hear: db independent solution.

I expect that my mapping works on different databases without changes. The fact that I have to define the name of the sequence for databases supporting sequences is OK for me: I don't expect (and even do not want) Hibernate to generate some sequence itself without "consulting" me - this would lead to endless problems (name conflicts etc.).

My humble opinion on the subject :-).

Erik

Erik, as you just said:
"I expect that my mapping works on different databases without changes."
is also my definition for database independent solution.
But if I use generator-class="native" like an such solution and I have to specify the sequence name, this is not an db independent solution because if I switch to another db I have to change the mapping.

I fail to understand where we disagree. I define

and then I know that on any database that supports sequences Hibernate will use sq_x to generate the id.

On a database supporting identity, it will ignore the sequence settings and generate the id using identity. So I can work on both type of databases without change to the mapping. That's how I understand db independence. It's a fact - and this is probably what you mean - that the mapping is not totally neutral and that Hibernate doesn't do all the work for us.

Maybe we should simply agree on the fact that we disagree :-), but it seems to be the way Hibernate supports db independence - though it doesn't deserve this name in your opinion.

Erik

That's Ok Erik.
I didn't know that what you said :
"On a database supporting identity, it will ignore the sequence settings and generate the id using identity" will function.
I thought that if I specify the name of the sequence on an db with identity I will get an error.

I have verified and that's working.

Thanks,
Cristian.