AW: Why vacuum?

> > > The tendency here seems to be towards an improved smgr.
> > > But, it is currently extremely cheap to calculate where a new row
> > > needs to be located physically. This task is *a lot* more expensive
> > > in an overwrite smgr.
>
> I don't agree. If (as I have proposed) the search is made in the
> background by a low priority process, you just have to lookup a cache
> entry to find out where to write.

If the priority is too low you will end up with the same behavior as current,
because the cache will be emptied by high priority multiple new rows,
thus writing to the end anyways. Conclusio: In those cases where overwrite would
be most advantageous (high volume modified table) your system won't work,
unless you resort to my concern and make it *very* expensive (=high priority).

Andreas