Horton

Re: pg15b2: large objects lost on upgrade

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: "Jonathan S. Katz" <jkatz@postgresql.org>
Cc: Robert Haas <robertmhaas@gmail.com>, 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: 2022-08-02T19:51:21Z
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.

"Jonathan S. Katz" <jkatz@postgresql.org> writes:
> On 8/2/22 3:39 PM, Tom Lane wrote:
>>> I am not in favor of disabling autovacuum in the test: ordinary
>>> users are not going to do that while pg_upgrade'ing, so it'd make
>>> the test less representative of real-world usage, which seems like
>>> a bad idea.  We could either drop this particular check again, or
>>> weaken it to allow new relfrozenxid >= old relfrozenxid, likewise
>>> relminxid.

> The test does look helpful and it would catch regressions. Loosely 
> quoting Robert on a different point upthread, we don't want to turn off 
> the alarm just because it's spuriously going off.
> I think the weakened check is OK (and possibly mimics the real-world 
> where autovacuum runs), unless you see a major drawback to it?

I also think that ">=" is a sufficient requirement.  It'd be a
bit painful to test if we had to cope with potential XID wraparound,
but we know that these installations haven't been around nearly
long enough for that, so a plain ">=" test ought to be good enough.
(Replacing the simple "eq" code with something that can handle that
doesn't look like much fun, though.)

			regards, tom lane