Horton

Re: pg15b2: large objects lost on upgrade

Bruce Momjian <bruce@momjian.us>

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From: Bruce Momjian <bruce@momjian.us>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Michael Paquier <michael@paquier.xyz>, Justin Pryzby <pryzby@telsasoft.com>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>, Shruthi Gowda <gowdashru@gmail.com>
Date: 2022-07-18T20:09:40Z
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 Mon, Jul 18, 2022 at 02:57:40PM -0400, Robert Haas wrote:
> So I tried implementing this but I didn't get it quite right the first
> time. It's not enough to call smgrdounlinkall() instead of
> RelationDropStorage(), because just as RelationDropStorage() does not
> actually drop the storage but only schedules it to be dropped later,
> so also smgrdounlinkall() does not in fact unlink all, but only some.
> It leaves the first segment of the main relation fork around to guard
> against the hazards discussed in the header comments for mdunlink().
> But those hazards don't really matter here either, because, again, any
> failure will necessarily require that the entire new cluster be
> destroyed, and also because there shouldn't be any concurrent activity
> in the new cluster while pg_upgrade is running. So I adjusted
> smgrdounlinkall() to actually remove everything when IsBinaryUpgrade =
> true. And then it all seems to work: pg_upgrade of a cluster that has
> had a rewrite of pg_largeobject works, and pg_upgrade of a cluster
> that has not had such a rewrite works too. Wa-hoo.

Using the IsBinaryUpgrade flag makes sense to me.

-- 
  Bruce Momjian  <bruce@momjian.us>        https://momjian.us
  EDB                                      https://enterprisedb.com

  Indecision is a decision.  Inaction is an action.  Mark Batterson