Horton

RE: Logical Replication of sequences

Hayato Kuroda (Fujitsu) <kuroda.hayato@fujitsu.com>

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From: "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>
To: 'shveta malik' <shveta.malik@gmail.com>, vignesh C <vignesh21@gmail.com>
Cc: Masahiko Sawada <sawada.mshk@gmail.com>, Nisha Moond <nisha.moond412@gmail.com>, Dilip Kumar <dilipbalaut@gmail.com>, Amit Kapila <amit.kapila16@gmail.com>, Peter Smith <smithpb2250@gmail.com>, Shlok Kyal <shlok.kyal.oss@gmail.com>, Peter Eisentraut <peter@eisentraut.org>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Euler Taveira <euler@eulerto.com>, Michael Paquier <michael@paquier.xyz>, "Zhijie Hou (Fujitsu)" <houzj.fnst@fujitsu.com>, "Jonathan S. Katz" <jkatz@postgresql.org>
Date: 2025-08-28T08:37:01Z
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. Doc: Add documentation for sequence synchronization.

  2. Remove unused assignment in CREATE PUBLICATION grammar.

  3. Add seq_sync_error_count to subscription statistics.

  4. Fix few issues in commit 5509055d69.

  5. Add sequence synchronization for logical replication.

  6. Add worker type argument to logical replication worker functions.

  7. Introduce "REFRESH SEQUENCES" for subscriptions.

  8. Refactor logical worker synchronization code into a separate file.

  9. Standardize use of REFRESH PUBLICATION in code and messages.

  10. Add "ALL SEQUENCES" support to publications.

  11. Expose sequence page LSN via pg_get_sequence_data.

  12. Resume conflict-relevant data retention automatically.

  13. Post-commit review fixes for 228c370868.

  14. Generate GUC tables from .dat file

Dear Shveta,

> Say we have triggered REFRESH on sub, and when seq-sync worker is in
> copy_sequences() where it has retrieved the local sequence using
> seqname while it has not locked the sequence-relation yet, if
> meanwhile we alter sequence and change its name, seq-sync worker ends
> up syncing that renamed sequence values with old-fetched sequence.
> Steps:

Personally not sure it should be fixed. IIUC, this could happen because the
sequence sync worker does not handle everything in the one transaction. However,
the transaction would be quite longer if we modify that.

From another perspective... assuming that the sequencesync worker has lock
during the synchronization. In your workload, the ALTER SEQUENCE command would
be delayed till the synchronization is done. In the end, the seq0 is synched
with the pub's seq0 then renamed to seq1 - eventually there are the same result.
Can you clarify if there are other problematic workloads?

Best regards,
Hayato Kuroda
FUJITSU LIMITED