How unique is an object id?

Is the automatically generated Id unique over different entities? If a record is deleted from a table, is it possible that a new record gets the deleted id?
1 answers

It is unique across the database, so across all entities.

No you will always get a unique ID. No reuse of IDs.

If you were to restore a database, for example to your laptop, be sure to either clean your local database during the restore or drop it entirely. I always drop it and create it fresh before the restore. If you just restore it over existing database objects, you have a big chance on duplicate IDs and far worse issues. A restore in the Mendix cloud takes care of this for you.