Hibernate version: 2.1.7
Name and version of the database you are using: Sybase

Hello all !
1)How does Hibernate generates an incremental id(primary key) !?
2)just when i call save !?
3)or when the transaction is commited ?!So hibernate calls select max and assign the key ?!
4) There is a chance to happens a "bug" , when Hibernate generates the same identifier to two different objects ?!


It´s better to use my own generated identifiers !?


Thank you very much!

Use the native generator.

Thank you david but i´m a newbie user and need some explanation about how Hibernate assigns an Id, how it works.
I did not find anything about my question.

Suppose i have two users doing an insert operation in different web transaction.

operationOne
session.save(objectOne)

1) now Hibernate goes to database select max id, add one and sets it to the object !?
2) or then just when the transaction is committed it´s assigned calling session.flush?



operationTwo
differentSession.save(objectTwo)

3) between that operation another is saving an object and assigns an id, so there is a possibility of two different objects to have the same identifier (selecting does not use lock) ?!
4) Even if hibernates generates it on transacion.commit() ?!


Sorry by english, and thanks again !

The native generator uses the native database's method of getting the next id usings its own semantics. For example, MSSQL uses an auto number so its the database's job to allocate the id when each record is inserted. Its the DBs responsibility to serialise this operation to guarantee no conflicts.