Horton

Re: pg_upgrade: transfer pg_largeobject_metadata's files when possible

Nathan Bossart <nathandbossart@gmail.com>

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From: Nathan Bossart <nathandbossart@gmail.com>
To: Andres Freund <andres@anarazel.de>
Cc: Michael Paquier <michael@paquier.xyz>, Tom Lane <tgl@sss.pgh.pa.us>, Nitin Motiani <nitinmotiani@google.com>, Hannu Krosing <hannuk@google.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2026-02-05T19:31:23Z
Lists: pgsql-hackers 
On Thu, Feb 05, 2026 at 01:02:17PM -0500, Andres Freund wrote:
> Upthread I also wondering why we do all the work in getLOs() if we don't
> actually need most of it (only if there are comments or labels).  Right now
> that's a very slow and very memory intensive part of doing an upgrade of a
> system with a lot of binary upgrades.  Do we need *any* of that if we go the
> path you suggest?

AFAICT we only need it for the comments and security labels later on.
Commit a45c78e3 did batch 1000 large objects into each ArchiveEntry, but of
course there can still be a ton of entries.  In theory, we could update the
pg_largeobject_metadata query to only retrieve LOs with comments and
security labels.  I'm not sure it's worth trying to optimize further than
that; we've long operated under the assumption that comments/seclabels on
LOs are pretty rare.

-- 
nathan

Commits

  1. pg_upgrade: Use COPY for LO metadata for upgrades from < v12.

  2. pg_upgrade: Fix handling of pg_largeobject_metadata.

  3. pg_upgrade: Transfer pg_largeobject_metadata's files when possible.

  4. Rearrange pg_dump's handling of large objects for better efficiency.

  5. Expand AclMode to 64 bits

  6. Fix pg_upgrade for oid removal.