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Re: Adding REPACK [concurrently]

Mihail Nikalayeu <mihailnikalayeu@gmail.com>

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From: Mihail Nikalayeu <mihailnikalayeu@gmail.com>
To: Antonin Houska <ah@cybertec.at>
Cc: Alvaro Herrera <alvherre@alvh.no-ip.org>, Pg Hackers <pgsql-hackers@lists.postgresql.org>, Robert Treat <rob@xzilla.net>
Date: 2026-01-12T18:54:56Z
Lists: pgsql-hackers 
Also, there are some crashes of stress tests for v30 (for both single
snapshot and multiple snapshot versions).

---------------------

Looks like something is leaking, but not sure.

https://cirrus-ci.com/task/5577209672368128?logs=test_world#L277 (multiple
snapshots)
https://cirrus-ci.com/task/6439044873191424 (without multiple snapshots)

[17:49:07.251] #   Failed test 'concurrent operations with REINDEX/CREATE
INDEX CONCURRENTLY stderr /(?^:^$)/'
[17:49:07.251] #   at /tmp/cirrus-ci-build/contrib/amcheck/t/
007_repack_concurrently.pl line 56.
[17:49:07.251] #                   'pgbench: error: client 0 script 0
aborted in command 6 query 0: ERROR:  out of background worker slots
[17:49:07.251] # HINT:  You might need to increase "max_worker_processes".
[17:49:07.251] # pgbench: error: Run was aborted due to an error in thread 0

-------------------

This one showed something goes wrong, the sum of the table is broken. It
may be 0 because non-MVCC safe, but I checked the logs:

2026-01-12 18:41:11.656 UTC client backend[76247] 007_repack_concurrently.pl
LOG:  statement: SELECT (490588) / 0;

And also

backend[54349] 007_repack_concurrently.pl ERROR:  could not create unique
index "tbl_pkey_repacknew"
2026-01-12 18:41:12.477 UTC client backend[54349] 007_repack_concurrently.pl
DETAIL:  Key (i)=(942) is duplicated.
2026-01-12 18:41:12.477 UTC client backend[54349] 007_repack_concurrently.pl
STATEMENT:  REPACK (CONCURRENTLY) tbl;

https://cirrus-ci.com/task/4521496594350080 (single snapshot version)
https://cirrus-ci.com/task/6157569896480768 (single snapshot version)

[18:36:17.466] #   at /Users/admin/pgsql/contrib/amcheck/t/
007_repack_concurrently.pl line 56.
[18:36:17.466] #                   'pgbench: error: client 21 script 0
aborted in command 31 query 0: ERROR:  division by zero
[18:36:17.466] # pgbench: error: Run was aborted due to an error in thread 2

---------------------

https://cirrus-ci.com/task/5682762788634624 (multiple snapshots)

 Failed test 'concurrent operations with REINDEX/CREATE INDEX CONCURRENTLY
stderr /(?^:^$)/'
[18:02:06.938] #   at t/007_repack_concurrently.pl line 56.
[18:02:06.938] #                   'pgbench: error: client 6 aborted in
command 4 (SQL) of script 0; perhaps the backend died while processing
[18:02:06.938] # pgbench: error: Run was aborted due to an error in thread 0
[18:02:06.938] # WARNING:  terminating connection because of crash of
another server process

Best regards,
Mikhail.

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