On Tue, Apr 16, 2013 at 4:48 AM, remk_1 <remk_1@...> wrote:

>
> I just made some nbackup tests (FB 2.5.2 SS, Windows XP) and noticed that
> whenever I use it to restore a database, it's Oldest transaction (OIT) gets
> stuck. It remains at the same value until next database sweep. Is it a bug
> or a feature ?
>
> 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.

Good luck,

Ann


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