Horton

Re: pg15b2: large objects lost on upgrade

Robert Haas <robertmhaas@gmail.com>

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From: Robert Haas <robertmhaas@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: "Jonathan S. Katz" <jkatz@postgresql.org>, Noah Misch <noah@leadboat.com>, Andrew Dunstan <andrew@dunslane.net>, Bruce Momjian <bruce@momjian.us>, Michael Paquier <michael@paquier.xyz>, Justin Pryzby <pryzby@telsasoft.com>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>, Shruthi Gowda <gowdashru@gmail.com>
Date: 2022-08-02T19:23:26Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Revert recent changes to 002_pg_upgrade.pl.

  2. Revise test case added in 43746996399541ecb5c7b188725a5f097c15ceae.

  3. Use TRUNCATE to preserve relfilenode for pg_largeobject + index.

  4. Preserve relfilenode of pg_largeobject and its index across pg_upgrade.

  5. Have VACUUM warn on relfrozenxid "in the future".

  6. Set relfrozenxid to oldest extant XID seen by VACUUM.

  7. pg_upgrade: Preserve relfilenodes and tablespace OIDs.

  8. Perform a lot more sanity checks when freezing tuples.

On Tue, Aug 2, 2022 at 1:12 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Not sure what to make of this, except that maybe the test is telling
> us about an actual bug of exactly the kind it's designed to expose.

That could be, but what would the bug be exactly? It's hard to think
of a more direct way of setting relminmxid and relfrozenxid than
updating pg_class. It doesn't seem realistic to suppose that we have a
bug where setting a column in a system table to an integer value
sometimes sets it to a slightly larger integer instead. If the values
on the new cluster seemed like they had never been set, or if it
seemed like they had been set to completely random values, then I'd
suspect a bug in the mechanism, but here it seems more believable to
me to think that we're actually setting the correct values and then
something - maybe autovacuum - bumps them again before we have a
chance to look at them.

I'm not quite sure how to rule that theory in or out, though.

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