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Re: Adding REPACK [concurrently]

Matthias van de Meent <boekewurm+postgres@gmail.com>

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From: Matthias van de Meent <boekewurm+postgres@gmail.com>
To: Alvaro Herrera <alvherre@alvh.no-ip.org>
Cc: Antonin Houska <ah@cybertec.at>, Mihail Nikalayeu <mihailnikalayeu@gmail.com>, Pg Hackers <pgsql-hackers@lists.postgresql.org>, Robert Treat <rob@xzilla.net>
Date: 2026-03-16T21:45:01Z
Lists: pgsql-hackers 
On Mon, 16 Mar 2026 at 20:34, Alvaro Herrera <alvherre@alvh.no-ip.org> wrote:
> On 2026-Mar-16, Matthias van de Meent wrote:
> > I agree it's not user-friendly, but that's the point of limiting
> > permissions. Users can't install c-functions without SUPERUSER,
> > because it can cause cluster instability and crashes. Users can't
> > create slots without REPLICATION, because they'll be able to
> > negatively impact the whole cluster's performance, and possibly,
> > stability, when taking up replication slots that otherwise would be
> > used for critical HA purposes.
>
> Well, as I said, these repack slots would be separate from the regular
> ones for replication and available only for repack, so they would not
> interfere with the count of slots used for replication, so the second
> point is moot, isn't it?

Sorry, I misread your response as "if at all, then at least like
this", instead of "let's do this alternative in this patch".

But, yes, a pool of slots used exclusively by REPACK CONCURRENTLY
would also solve the slot availability issue.

Kind regards,

Matthias van de Meent
Databricks (https://www.databricks.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