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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>, Srinath Reddy Sadipiralla <srinath2133@gmail.com>, Matthias van de Meent <boekewurm+postgres@gmail.com>, Pg Hackers <pgsql-hackers@lists.postgresql.org>, Robert Treat <rob@xzilla.net>
Date: 2026-03-27T16:12:55Z
Lists: pgsql-hackers 
Antonin Houska <ah@cybertec.at> wrote:

> Mihail Nikalayeu <mihailnikalayeu@gmail.com> wrote:

> > src/backend/catalog/index.c:766,1464-1469
> > 
> > "bool      progress = (flags & INDEX_CREATE_REPORT_PROGRESS) != 0;"
> > 
> > AFAIU gin, hash and btree (at least) still just unconditionally write
> > PROGRESS_CREATEIDX_* progress.
> 
> I think you're right, I'll check it.

I concluded this is a problem that exists for quite a while and should be
fixed separately. Currently I don't see conflicts of parameter indexes between
PROGRESS_COMMAND_REPACK and PROGRESS_COMMAND_CREATE_INDEX. There would be some
if the index was built with the CONCURRENTLY option, but REPACK uses normal
index build.

I tried to write a patch that allows progress tracking of two commands at the
same time (a "main command" and a "subcommand"), but regression tests revealed
that contrib/file_fdw is broken in a way that I could not fix easily: during
execution of a join, two COPY FROM commands are executed at the same time and
they overwrite the status of each other. Unlike the concept of a sub-command,
we cannot assume here that the command that started the reporting as the
second will stop as the first. Thus in pgstat_progress_end_command() we cannot
figure out which node is trying to stop the reporting.

It needs more work, I can get back to it after PG 19 feature freeze.

-- 
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