Re: The Free Space Map: Problems and Opportunities

On Fri, Aug 20, 2021 at 11:48 AM Peter Geoghegan <pg(at)bowt(dot)ie> wrote:
> On Fri, Aug 20, 2021 at 7:45 AM Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> > I very much doubt that you can get away without some sort of free
> > space map. Even if in most cases most pages are closed to insertions,
> > there will be important corner cases where lots of pages are open for
> > insertions, like when you just deleted a ton of rows and then ran
> > VACUUM. And we cannot lose track of even one of those open pages or,
> > if the pre-8.4 state of the world is any indication, we will be super
> > sad.
>
> I agree with all that. The point I was making is that this new FSM
> design will have an on-disk size that is "a function of the workload".

That could be the right decision, but nothing said up to this point
really seems to suggest it. The open/closed distinction and the
changes in how to bin available space could all be done with the
present model.

--
Robert Haas
EDB: http://www.enterprisedb.com