Re: Overhauling "Routine Vacuuming" docs, particularly its handling of freezing

Maciek Sakrejda <m.sakrejda@gmail.com>

From: Maciek Sakrejda <m.sakrejda@gmail.com>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Peter Geoghegan <pg@bowt.ie>, John Naylor <john.naylor@enterprisedb.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2023-05-01T19:03:38Z
Lists: pgsql-hackers
On Mon, May 1, 2023, 18:08 Robert Haas <robertmhaas@gmail.com> wrote:

> I am saying that, while wraparound is perhaps not a perfect term
> for what's happening, it is not, in my opinion, a bad term either.


I don't want to put words into Peter's mouth, but I think that he's arguing
that the term "wraparound" suggests that there is something special about
the transition between xid 2^32 and xid 0 (or, well, 3). There isn't.
There's only something special about the transition, as your current xid
advances, between the xid that's half the xid space ahead of your current
xid and the xid that's half the xid space behind the current xid, if the
latter is not frozen. I don't think that's what most users think of when
they hear "wraparound".

Commits

  1. Fix the race condition in the test case added by commit a6e04b1d20.

  2. Add page-level freezing to VACUUM.