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Re: Adding REPACK [concurrently]

Antonin Houska <ah@cybertec.at>

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From: Antonin Houska <ah@cybertec.at>
To: Andres Freund <andres@anarazel.de>
Cc: Alvaro Herrera <alvherre@alvh.no-ip.org>, Amit Kapila <amit.kapila16@gmail.com>, Mihail Nikalayeu <mihailnikalayeu@gmail.com>, Srinath Reddy Sadipiralla <srinath2133@gmail.com>, Matthias van de Meent <boekewurm+postgres@gmail.com>, Pg Hackers <pgsql-hackers@lists.postgresql.org>, Robert Treat <rob@xzilla.net>
Date: 2026-04-07T16:01:16Z
Lists: pgsql-hackers 
Andres Freund <andres@anarazel.de> wrote:

> On 2026-04-07 17:38:24 +0200, Antonin Houska wrote:
> > The REPACK plugin only deforms tuples and writes them to a file, so I think
> > that things like this should not happen.
> 
> You don't need to do it yourself.  It just requires a shared_preload_library
> extension to register a relcache invalidation callback that accesses shared
> catalog.
> 
> It's only kind of an accident that we don't have a case today that accesses
> shared catcaches during a relcache build in core (I'm not even sure there's
> nothing). You'd just need somebody to add e.g. relcache caching for
> publications for that to change. Or look up information about a reloption in
> pg_parameter_acl. Or lookup tablespace configuration.
> 
> 
> > However, I admit that an option that allows the plugin developer to declare
> > "I don't need shared catalogs" may be considered deceptive.
> 
> At the very least it would need to be a runtime check rather than just an
> assert. This would much more likely to be hit in production because otherwise
> it's probably hard to hit the case where shared invalidations happen in the
> wrong moment.  And the consequences are corrupted caches, which could cause
> all kinds of havoc.
> 
> 
> But I think this may need more infrastructure / deeper analysis than what we
> can do right now.

ok, thanks a lot for having looked at it.

-- 
Antonin Houska
Web: https://www.cybertec-postgresql.com

Commits

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

  1. Allow old WAL recycling during REPACK CONCURRENTLY

  2. Advance restart_lsn more eagerly in LogicalConfirmReceivedLocation

  3. Remove unnecessary signal handler change

  4. Improve REPACK (CONCURRENTLY) error messages some more

  5. Revert "Allow logical replication snapshots to be database-specific"

  6. Move REPACK (CONCURRENTLY) test out of stock regression tests

  7. REPACK: do not require REPLICATION or LOGIN

  8. Add missing initialization

  9. Simplify declaration of memcpy target

  10. Reserve replication slots specifically for REPACK

  11. doc: Add an example of REPACK (CONCURRENTLY)

  12. Allow logical replication snapshots to be database-specific

  13. Avoid different-size pointer-to-integer cast

  14. Fix valgrind failure

  15. Add CONCURRENTLY option to REPACK

  16. Rename cluster.c to repack.c (and corresponding .h)

  17. Allow index_create to suppress index_build progress reporting

  18. Make index_concurrently_create_copy more general

  19. Document the 'command' column of pg_stat_progress_repack

  20. Introduce the REPACK command

  21. Toggle logical decoding dynamically based on logical slot presence.

  22. Split vacuumdb to create vacuuming.c/h

  23. Remove ReorderBufferTupleBuf structure.

  24. Revert changes to CONCURRENTLY that "sped up" Xmin advance

  25. VACUUM: ignore indexing operations with CONCURRENTLY