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Re: [UNVERIFIED SENDER] Re: pg_upgrade can result in early wraparound on databases with high transaction load

Peter Geoghegan <pg@bowt.ie>

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From: Peter Geoghegan <pg@bowt.ie>
To: Andrew Dunstan <andrew@dunslane.net>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Bruce Momjian <bruce@momjian.us>, "Drouvot, Bertrand" <bdrouvot@amazon.com>, Andres Freund <andres@anarazel.de>, Justin Pryzby <pryzby@telsasoft.com>, Noah Misch <noah@leadboat.com>, Jason Harvey <jason@reddit.com>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>, "Tharakan, Robins" <tharar@amazon.com>
Date: 2022-07-05T19:50:12Z
Lists: pgsql-hackers, pgsql-general 
On Tue, Jul 5, 2022 at 12:41 PM Peter Geoghegan <pg@bowt.ie> wrote:
> Actually, commit 74cf7d46 was where pg_resetxlog/pg_resetwal's -u
> argument was first added, for use by pg_upgrade. That commit is only
> about a year old, and was only backpatched to 9.6.

I just realized that this thread was where that work was first
discussed. That explains why it took a year to discover that we broke
8.4!

On further reflection I think that breaking pg_upgrade for 8.4 might
have been a good thing. The issue was fairly visible and obvious if
you actually ran into it, which is vastly preferable to what would
have happened before commit 74cf7d46.

-- 
Peter Geoghegan

Commits

  1. Refuse upgrades from pre-9.0 clusters

  2. pg_resetxlog: add option to set oldest xid & use by pg_upgrade

  3. Stamp 11.2.

  4. Track the current XID wrap limit (or more accurately, the oldest unfrozen