Thanks for further explanation, Ann and Sean. I'm basically aware of those differences between gbak and nbackup, but I should have noted that the OIT in the original database is ok and moving forward.

> Nbackup takes physical snapshots of pages as they change. It wouldn't
> recognize a record or a transaction if it fell over one. So a database
> restored from nbackup is physically identical to the database it
> reproduces. Transaction numbers stay the same, old versions stay in place,
> and any "interesting" old versions stay too.

The original database has all transaction numbers moving forward (there are all about the same +- 2). But when I do a level 0 nbackup backup and then restore it, the OIT in the restored database gets frozen. So although transactions numbers stay the same, there must be some difference between the original and restored database. I found that it is caused solely by the nbackup restore (not by nbackup backup), because when I work with the original database from which I made the backup, the OIT still goes on freely.

Probably this is just an unimportant side effect of nbackup use, I just wanted to be sure that it won't affect negatively database performance.

Thanks again,
Michal