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Re: Adding REPACK [concurrently]

Mihail Nikalayeu <mihailnikalayeu@gmail.com>

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From: Mihail Nikalayeu <mihailnikalayeu@gmail.com>
To: Alvaro Herrera <alvherre@alvh.no-ip.org>
Cc: Antonin Houska <ah@cybertec.at>, Srinath Reddy Sadipiralla <srinath2133@gmail.com>, Amit Kapila <amit.kapila16@gmail.com>, Matthias van de Meent <boekewurm+postgres@gmail.com>, Pg Hackers <pgsql-hackers@lists.postgresql.org>, Robert Treat <rob@xzilla.net>
Date: 2026-04-06T10:14:57Z
Lists: pgsql-hackers 
Hello!

On Sun, Apr 5, 2026 at 10:41 PM Alvaro Herrera <alvherre@alvh.no-ip.org> wrote:
> So here's a v55 version of the base REPACK patches that I'm feeling
> comfortable calling very close to committable.

Some comments for v55.

repack.c:2725

    if (!VARATT_IS_EXTERNAL(varlen))
          continue;

I think it should be VARATT_IS_EXTERNAL_INDIRECT - the same as in pgrepack:244.

Also,  after

natt_ext--;

I think it worth to add

Assert(natt_ext >= 0);

or Assert(natt_ext == 0); but in another place.

Or exit early with
     for (int i = 0; i < desc->natts && natt_ext > 0; i++)

----------------------------
repack.c:2587

    table_tuple_insert(rel, slot, GetCurrentCommandId(true),
       HEAP_INSERT_NO_LOGICAL, NULL);

More idiomatic to use TABLE_INSERT_NO_LOGICAL instead.

----------------------------
repack.c:2696

     ExecForceStoreHeapTuple(tup, slot, false);

AFAIU there is a memory leak here. Memory allocated above (for tuple)
is not freed in any way, because shouldFree == false.
Also, ExecClearTuple (tts_virtual_clear for virtual tuples) requires
TTS_SHOULDFREE to be set to free anything.

-------------------------
grab ShareUpdateExclusiveLock (jsut like VACUUM

typo in "just"

--------------------------

"If the identity index is not set due to replica identity being, PK"

Missing "FULL" after "being"?

-------------------------

Commit message:

"intial copy" -> "initial copy"
"backed performing REPACK" -> "backend performing REPACK"


Best regards,
Mikhail.

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