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Re: Adding REPACK [concurrently]

Alexander Lakhin <exclusion@gmail.com>

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From: Alexander Lakhin <exclusion@gmail.com>
To: Antonin Houska <ah@cybertec.at>, Alvaro Herrera <alvherre@alvh.no-ip.org>
Cc: Amit Kapila <amit.kapila16@gmail.com>, "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>, Srinath Reddy Sadipiralla <srinath2133@gmail.com>, Mihail Nikalayeu <mihailnikalayeu@gmail.com>, Matthias van de Meent <boekewurm+postgres@gmail.com>, Pg Hackers <pgsql-hackers@lists.postgresql.org>, Robert Treat <rob@xzilla.net>
Date: 2026-04-12T14:00:00Z
Lists: pgsql-hackers 
Hello Antonin and Alvaro,

10.04.2026 13:57, Antonin Houska wrote:
> Attached is a fix that works for me.
>
> Nevertheless, REPACK (CONCURRENTLY) in your test goes ahead only due to commit
> 0d3dba38c7, which will probably be reverted [1]. Then REPACK will wait for the
> transaction in the other database (db1) to complete before it can actually
> start.

Thank you for the fix!

I've stumbled upon one more issue with this feature:
CREATE TABLE t (i int PRIMARY KEY);
REPACK (CONCURRENTLY) t;

fails for me with sanitizers enabled and
min_dynamic_shared_memory = '1GB'
in postgresql.conf as below:
2026-04-12 13:23:02.000 UTC [2733633] LOG:  statement: REPACK (CONCURRENTLY) t;
repack.c:3373:15: runtime error: load of value 240, which is not a valid value for type '_Bool'
     #0 0x6441f7eba454 in start_repack_decoding_worker .../src/backend/commands/repack.c:3373
     #1 0x6441f7ebdaad in rebuild_relation .../src/backend/commands/repack.c:1010
     #2 0x6441f7ebe9a2 in cluster_rel .../src/backend/commands/repack.c:656
     #3 0x6441f7ebefea in process_single_relation .../src/backend/commands/repack.c:2359
     #4 0x6441f7ebf870 in ExecRepack .../src/backend/commands/repack.c:296
     #5 0x6441f886f20e in standard_ProcessUtility .../src/backend/tcop/utility.c:867
...

2026-04-12 13:23:03.620 UTC [2733620] LOG:  client backend (PID 2733633) was terminated by signal 6: Aborted
2026-04-12 13:23:03.620 UTC [2733620] DETAIL:  Failed process was running: REPACK (CONCURRENTLY) t;

Could you please have a look?

Best regards,
Alexander

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