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Re: Adding REPACK [concurrently]

Robert Treat <rob@xzilla.net>

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From: Robert Treat <rob@xzilla.net>
To: Alvaro Herrera <alvherre@alvh.no-ip.org>
Cc: Mihail Nikalayeu <mihailnikalayeu@gmail.com>, Antonin Houska <ah@cybertec.at>, Srinath Reddy Sadipiralla <srinath2133@gmail.com>, Amit Kapila <amit.kapila16@gmail.com>, Matthias van de Meent <boekewurm+postgres@gmail.com>, Pg Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2026-04-07T19:43:50Z
Lists: pgsql-hackers 
On Mon, Apr 6, 2026 at 6:22 PM Alvaro Herrera <alvherre@alvh.no-ip.org> wrote:
> On 2026-Apr-06, Mihail Nikalayeu wrote:
<snip>
>
> Anyway, here's the three missing parts.  I have not yet edited the
> deadlock-checker one to protect autovacuum from processing tables under
> repack.
>

I have this lingering bit of paranoia that users could end up in a
situation with a large / long running repack that goes past failsafe
age which prevents the simpler fix of failsafe autovacuum from
running. While the repack finishing would resolve this issue, we can't
know ahead of time that the repack would finish in time, and
statistically speaking, failsafe autovacuum should generally run much
quicker than any repack could. I'm not sure if that means we should
let failsafe vacuum cancel repacks (that seems a bit extreme), but
maybe we want to help $operator to think about this decision, except
if we don't allow autovacuum to wait and we don't allow it to respawn,
I wonder if the end user will ever realize they are in this position.
Granted, there doesn't seem like a clean fix for this...

Robert Treat
https://xzilla.net

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