--- In firebird-support@yahoogroups.com, Ann Harrison <aharrison@...> wrote:

> >
> > The Oldest Interesting Transaction (OIT) is the oldest transaction in the
> system that is not committed. Ordinarily, that's a transaction that rolled
> back and could not be cleaned up automatically. Only sweep can change the
> OIT. The Oldest Active Transaction should move freely, unless you've got
> a long running transaction. The OAT blocks garbage collection and causes
> performance problems. The OIT is much less interesting. It does require
> that every transaction have access to a bitmap of transaction states
> between the OIT and the Next Transaction, but that's much less of an issue
> than it was when machines had memory measured in megabyte rather than gigs.
> So, neither a bug nor a features. Just an artifact.

Ann, thanks for the explanation. The OAT moves freely, it's really just the OIT that is blocked. I still don't understand why it stops just because of database restore (only through nbackup, gbak is ok), but if it's not going to cause a performance penalty, it's not an important issue.

Regards,
Michal