| From: | Peter Geoghegan <pg(at)bowt(dot)ie> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
| Cc: | Andres Freund <andres(at)anarazel(dot)de>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, Jan Wieck <jan(at)wi3ck(dot)info>, Gregory Smith <gregsmithpgsql(at)gmail(dot)com>, John Naylor <john(dot)naylor(at)enterprisedb(dot)com>, Heikki Linnakangas <hlinnaka(at)iki(dot)fi> |
| Subject: | Re: The Free Space Map: Problems and Opportunities |
| Date: | 2021-08-20 16:16:58 |
| Message-ID: | CAH2-Wzm1jUnK-BySw+7doYvsg8k7QGuqwg7kq9XEJzPnRR_vcg@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Fri, Aug 20, 2021 at 9:03 AM Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> 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.
I guess that's true. Isn't this just semantics, though?
The new FSM implementation certainly cannot forget about pages that it
deems open, or fail to have information about pages that should be
considered open -- that would be absolutely unacceptable. And the
implementation cannot assume that it won't have to maintain
information about every single heap page. All I'm saying is that in
practice this will be very rare. Making the FSM structure smaller
isn't really the goal, though.
--
Peter Geoghegan
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