Re: Adding REPACK [concurrently]

Mikhail Nikalayeu <mihailnikalayeu@gmail.com>

From: Mihail Nikalayeu <mihailnikalayeu@gmail.com>

To: Antonin Houska <ah@cybertec.at>

Cc: Alvaro Herrera <alvherre@alvh.no-ip.org>, Fujii Masao <masao.fujii@gmail.com>, Robert Treat <rob@xzilla.net>, Pg Hackers <pgsql-hackers@lists.postgresql.org>

Date: 2025-08-25T18:18:17Z

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 →

Improve REPACK (CONCURRENTLY) error messages some more
- 378dffaf8c80 19 (unreleased) landed
Add CONCURRENTLY option to REPACK
- 28d534e2ae0a 19 (unreleased) landed
Make index_concurrently_create_copy more general
- 33bf7318f94c 19 (unreleased) landed
Document the 'command' column of pg_stat_progress_repack
- a630ac5c2016 19 (unreleased) landed
Introduce the REPACK command
- ac58465e0618 19 (unreleased) landed
Split vacuumdb to create vacuuming.c/h
- c4067383cb2c 19 (unreleased) landed
Revert changes to CONCURRENTLY that "sped up" Xmin advance
- 042b584c7f7d 14.4 cited

Antonin Houska <ah@cybertec.at>:
> I think the problem is that HeapTupleSatisfiesSelf() uses
> TransactionIdIsInProgress() instead of checking the snapshot:

Yes, some issues might be possible for SnapshotSelf.
Possible solution is to override TransactionIdIsCurrentTransactionId
to true (like you did with nParallelCurrentXids but just return true).
IIUC, in that case all checks are going to behave the same way as in v5 version.

> I'd prefer optimization of the logical decoding for REPACK CONCURRENTLY, and
> using the MVCC snapshots.

It is also possible, but it is much more complex and feels like overkill to me.
We need just a way to find the latest version of row in the world of
all-committed transactions without any concurrent writers - I am
pretty sure it is possible to achieve in a more simple and effective
way.