Re: Automatic free space map filling

On Thu, Mar 02, 2006 at 01:01:21AM -0500, Tom Lane wrote:
> > Essentially, we would be folding the "find
> > dead tuples and compress page" logic, which is currently in vacuum, back
> > to insert. IMHO this is unacceptable from a performance PoV.
>
> That's the other problem: it's not apparent why pushing work from vacuum
> back into foreground processing is a good idea. Especially not why
> retail vacuuming of individual tuples will be better than wholesale.

The problem is that even with vacuum_cost_delay, vacuum is still very
slow and problematic in situations such as a large tables in a heavy
transaction environment. Anything that could help reduce the need for
'traditional' vacuuming could well be a win.

Even so, I think the most productive path to pursue at this time is a
dead-space-map/known-clean-map. Either one is almost guaranteed to
provide benefits. Once we know what good they do we can move forward
from there with further improvements.
--
Jim C. Nasby, Sr. Engineering Consultant jnasby(at)pervasive(dot)com
Pervasive Software http://pervasive.com work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461