What does 'Compact' feature do?

[vspazv]

I compacted a large group the other day and it went from 20 GB to 20.8 GB... I'm pretty sure that wasn't the goal.

[Quade]

It basically re-organizes and defragments the DB. If you'd done some big deletes, it would recover space. If there was no space to recover it won't. I've seen them get bigger after a compact. I think it doesn't something to the indexes.

Compact will speed up the DB operations and can make the file smaller if you deleted from it.

If you want to recover some space, the best way is to reduce the "Storage Age", update the group by downloading latest headers, then doing a compact. Most servers aren't really reliable out beyond 1400 days these days so keeping more than that is probably not necessary.