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
