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Re: Adding REPACK [concurrently]

Antonin Houska <ah@cybertec.at>

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From: Antonin Houska <ah@cybertec.at>
To: Mihail Nikalayeu <mihailnikalayeu@gmail.com>
Cc: Alvaro Herrera <alvherre@alvh.no-ip.org>, Pg Hackers <pgsql-hackers@lists.postgresql.org>, Robert Treat <rob@xzilla.net>
Date: 2026-02-02T07:25:48Z
Lists: pgsql-hackers 
Mihail Nikalayeu <mihailnikalayeu@gmail.com> wrote:

> > The 0006 part needs more work (definitely beyond PG 19).
> 
> This is sad, because if you are in a situation then you need REPACK - pinning the horizon for too long may just finish your DB....
> And also, even with 0006 we still need to build indexes, which might pin it for long (even duration caused by a single index).

I suppose "to finish database" refers to XID wraparound - a problem that you
keep mentioning again and again. (Yes, the wraparound is a problem, but not
exactly a "final" state of the database.)

As far as I know, it's not uncommon for DBAs to use the pg_repack extension,
and this extension also restricts the progress of the VACUUM xmin horizon. Are
you sure that users do complain about having ended up in the XID wraparound
situation?

I don't really pay attention to pg_repack, but I do pay quite some attention
to the pg_squeeze extension (which I wrote and maintain). I recall that some
users were surprised by the amount of disk space consumed (as the earlier
versions of pg_squeeze were "too lazy" about WAL decoding), but I do not
recall a single complaint about pg_squeeze causing the XID wraparound
situation.

-- 
Antonin Houska
Web: https://www.cybertec-postgresql.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