Horton

Re: Adding REPACK [concurrently]

Mikhail 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: 2025-12-02T00:50:00Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Improve REPACK (CONCURRENTLY) error messages some more

  2. Add CONCURRENTLY option to REPACK

  3. Make index_concurrently_create_copy more general

  4. Document the 'command' column of pg_stat_progress_repack

  5. Introduce the REPACK command

  6. Split vacuumdb to create vacuuming.c/h

  7. Revert changes to CONCURRENTLY that "sped up" Xmin advance

Hello, Antonin!

On Mon, Nov 3, 2025 at 8:56 AM Antonin Houska <ah@cybertec.at> wrote:
> I'll fix all the problems in the next version. Thanks!

A few more moments I mentioned:

> switch ((vis = HeapTupleSatisfiesVacuum(tuple, OldestXmin, buf)))
vis is unused, also to double braces.

>       LockBuffer(buf, BUFFER_LOCK_UNLOCK);
>       continue;
>    }

>    /*
>     * In the concurrent case, we have a copy of the tuple, so we
>     * don't worry whether the source tuple will be deleted / updated
>     * after we release the lock.
>     */
>    LockBuffer(buf, BUFFER_LOCK_UNLOCK);
>}

I think locking and comments are a little bit confusing here.
I think we may use single LockBuffer(buf, BUFFER_LOCK_UNLOCK); before
`if (isdead)` as it was before.
Also, I am not sure "we have a copy" is the correct point here, I
think motivation is mostly the same as in
heapam_index_build_range_scan.

Also, I think it is a good idea to add tests for index-based and
sort-based repack.

Also, for sort-based I think we need to also call
repack_decode_concurrent_changes during insertion phase

> is_system_catalog && !concurrent
2 places, always true, feels strange.

Best regards,
Mikhail.