Curious about Firefox "Compacting Database" tickmark

Hey all,

I have been wondering for a while now, how the 'Compact Database' tickmark does it's work for Firefox.

I currently run CCleaner with that option checked, but before it gets to that point, I use SQLite3 to clean (vacuum is the term used) the *.sqlite files. Is this the same (or similar) to what (and which files) CCleaner compacts?

If not, where and how does it 'compact'? Seems to take a while usually, not that the normal cache deletion doesn't.

It is the same, it vaccuumes the database