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Re: Adding REPACK [concurrently]

Alvaro Herrera <alvherre@alvh.no-ip.org>

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From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: Antonin Houska <ah@cybertec.at>
Cc: 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: 2026-03-26T23:14:50Z
Lists: pgsql-hackers 
On 2026-Mar-26, Antonin Houska wrote:

> I haven't thought of it because I'm not familiar with the deadlock detector,
> but what you do seems consistent with the way blocking by autovacuum is
> handled.
> 
> The only problem I noticed is that PROC_IN_CONCURRENT_REPACK is not cleared at
> the end of transaction. Perhaps it should be added to PROC_VACUUM_STATE_MASK
> (name of which is already misleading due to the presence of PROC_IN_SAFE_IC,
> but that's another problem).

Yeah, good observation -- we should absolutely clear it at transaction
end, and adding it to PROC_VACUUM_STATE_MASK seems the cleanest way to
make that happen.  However, we should also clear it as soon as we've
acquired the AccessExclusiveLock on all rels.  At that point we no
longer need it, and it makes more sense to have other transactions
resume the normal waiting behavior instead of having them fail right
away.

> Maybe just add a new permutation to repack.spec? I don't remembery if I
> created repack_toast.spec as a separate file just for better readability or if
> there was some other issue, but the deadlock test might fit into repack.spec.

Yeah, that was my first impulse too, but it's not clear to me that
things are better one way or the other.  I haven't decided yet.

-- 
Álvaro Herrera               48°01'N 7°57'E  —  https://www.EnterpriseDB.com/
"[PostgreSQL] is a great group; in my opinion it is THE best open source
development communities in existence anywhere."                (Lamar Owen)

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