Re: Automatic free space map filling

On Wed, Mar 01, 2006 at 12:41:01PM -0500, Tom Lane wrote:
> Peter Eisentraut <peter_e@gmx.net> writes:
> > Tom Lane wrote:
> >> How does an optimistic FSM entry avoid the need to run vacuum?
> 
> > It ensures that all freed tuples are already in the FSM.
> 
> That has nothing to do with it, because the space isn't actually free
> for re-use until vacuum deletes the tuple.
> 

Hmm, but couldn't such an opportunistic approach be used for another leightweight VACUUM mode in such a 
way, that VACUUM could look at a special "Hot Spot" queue, which represents potential candidates for 
freeing? Let's call it a 2-phase VACUUM....this would avoid a long running VACUUM run on big tables, 
e.g. when tuples gets updated (or deleted) frequently. Just an idea...

        Bernd