Horton

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

x4mmm@yandex-team.ru

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From: "Andrey M. Borodin" <x4mmm@yandex-team.ru>
To: Robert Haas <robertmhaas@gmail.com>
Cc: "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Date: 2020-07-14T06:25:17Z
Lists: pgsql-hackers 
Hi!

> 14 июля 2020 г., в 02:12, Robert Haas <robertmhaas@gmail.com> написал(а):
> 
> So I have these questions:
> 
> - Do people think it would me smart/good/useful to include something
> like this in PostgreSQL?
> 
> - If so, how? I would propose a new contrib module that we back-patch
> all the way


My 0.05₽.

At Yandex we used to fix similar corruption things with our pg_dirty_hands extension [0].
But then we developed our internal pg_heapcheck module (unfortunately we did not publish it) and incorporated aggressive recovery into heapcheck.

Now when community has official heapcheck I think it worth to keep detection and fixing tools together.

Best regards, Andrey Borodin.

[0] https://github.com/dsarafan/pg_dirty_hands/blob/master/src/pg_dirty_hands.c

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.