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Re: Adding REPACK [concurrently]

Alexander Lakhin <exclusion@gmail.com>

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From: Alexander Lakhin <exclusion@gmail.com>
To: Alvaro Herrera <alvherre@alvh.no-ip.org>, Amit Kapila <amit.kapila16@gmail.com>
Cc: "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>, Antonin Houska <ah@cybertec.at>, Srinath Reddy Sadipiralla <srinath2133@gmail.com>, Mihail Nikalayeu <mihailnikalayeu@gmail.com>, Matthias van de Meent <boekewurm+postgres@gmail.com>, Pg Hackers <pgsql-hackers@lists.postgresql.org>, Robert Treat <rob@xzilla.net>
Date: 2026-04-10T07:00:00Z
Lists: pgsql-hackers 
Hello Alvaro,

08.04.2026 00:38, Alvaro Herrera wrote:
> Okay.  I implemented that now, and here it is.  ...

Could you please look at an assertion failure produced by the following
script, starting from 0d3dba38c:?
createdb db1
createdb db2

echo "
CREATE TABLE t0 (a text);
BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE;
INSERT INTO t0 VALUES ('a');
SELECT pg_sleep(1);
" | psql db1 &

echo "
CREATE TABLE t1 (id int PRIMARY KEY);
CREATE TABLE t2 (id int PRIMARY KEY, a TEXT, FOREIGN KEY (id) REFERENCES t1);
SET min_parallel_table_scan_size = 1;
REPACK (CONCURRENTLY) t2;
" | psql db2
wait

It triggers for me:
TRAP: failed Assert("TransactionIdPrecedesOrEquals(TransactionXmin, RecentXmin)"), File: "procarray.c", Line: 2071, PID: 
3529520
postgres: parallel worker for PID 3529517 (ExceptionalCondition+0x69)[0x62f724b19c4c]
postgres: parallel worker for PID 3529517 (+0x522456)[0x62f72498e456]
postgres: parallel worker for PID 3529517 (GetSnapshotData+0x6b)[0x62f72498f50c]
postgres: parallel worker for PID 3529517 (GetNonHistoricCatalogSnapshot+0x4b)[0x62f724b5bd90]
postgres: parallel worker for PID 3529517 (GetCatalogSnapshot+0x20)[0x62f724b5ce7b]
postgres: parallel worker for PID 3529517 (systable_beginscan+0x10b)[0x62f7245c31e7]
postgres: parallel worker for PID 3529517 (+0x69e1e7)[0x62f724b0a1e7]
postgres: parallel worker for PID 3529517 (+0x69e5a6)[0x62f724b0a5a6]
postgres: parallel worker for PID 3529517 (+0x6a4d86)[0x62f724b10d86]
postgres: parallel worker for PID 3529517 (RelationIdGetRelation+0x83)[0x62f724b11208]
postgres: parallel worker for PID 3529517 (relation_open+0x1e)[0x62f72456c235]
...
2026-04-10 05:59:51.471 UTC [3529495] LOG:  background worker "parallel worker" (PID 3529520) was terminated by signal 
6: Aborted

Best regards,
Alexander

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