Horton

Re: recovering from "found xmin ... from before relfrozenxid ..."

Robert Haas <robertmhaas@gmail.com>

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From: Robert Haas <robertmhaas@gmail.com>
To: Andrey Borodin <x4mmm@yandex-team.ru>
Cc: Andres Freund <andres@anarazel.de>, Tom Lane <tgl@sss.pgh.pa.us>, Amit Kapila <amit.kapila16@gmail.com>, Ashutosh Sharma <ashu.coek88@gmail.com>, Mark Dilger <mark.dilger@enterprisedb.com>, Masahiko Sawada <masahiko.sawada@2ndquadrant.com>, MBeena Emerson <mbeena.emerson@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Peter Eisentraut <peter.eisentraut@2ndquadrant.com>, Stephen Frost <sfrost@snowman.net>
Date: 2021-01-18T13:54:10Z
Lists: pgsql-hackers 
On Sat, Jan 16, 2021 at 10:41 AM Andrey Borodin <x4mmm@yandex-team.ru> wrote:
> Does anyone maintain opensource pg_surgery analogs for released versions of PG?
> It seems to me I'll have to use something like this and I just though that I should consider pg_surgery in favour of our pg_dirty_hands.

I do not. I'm still of the opinion that we ought to back-patch
pg_surgery. This didn't attract a consensus before, and it's hard to
dispute that it's a new feature in what would be a back branch. But
it's unclear to me how users are otherwise supposed to recover from
some of the bugs that are or have been present in those back branches.
I'm not sure that I see the logic in telling people we'll try to
prevent them from getting hosed in the future but if they're already
hosed they can wait for v14 to fix it. They can't wait that long, and
a dump-and-restore cycle is awfully painful.

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

Commits

  1. Fix wrong data table horizon computation during backend startup.

  2. Centralize horizon determination for temp tables, fixing bug due to skew.

  3. pg_surgery: Try to stabilize regression tests.

  4. New contrib module, pg_surgery, with heap surgery functions.

  5. Set cutoff xmin more aggressively when vacuuming a temporary table.

  6. snapshot scalability: Don't compute global horizons while building snapshots.

  7. Introduce vacuum errcontext to display additional information.