Can we upgrade an Oracle SDE geodatabase from 9.3 to 10.0 or 10.2 with plenty of version unposted?
When we try to upgrade an SDE instance there are always versions that are not posted. Are these version migrated?
The upgrade process should not touch the versions in the geodatabase. The upgrade process is usually upgrading the geodatabase repository table, stored procedures, triggers, etc... to add the latest functionality. I would also recommend a reconcile/post on as many versions as possible, then run a compress to clear out the delta tables as much as possible. This will help improve the upgrade process.
With that being said, it is recommended that you test the upgrade on a DEV machine first to make sure that everything appears correct after the upgrade and works as expected.
Here is some documentation that cover the steps for a successful upgrade to 10.2.x:
Hopefully this helps.