Horton

Re: Logical Replication of sequences

shveta malik <shveta.malik@gmail.com>

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From: shveta malik <shveta.malik@gmail.com>
To: vignesh C <vignesh21@gmail.com>
Cc: Nisha Moond <nisha.moond412@gmail.com>, Amit Kapila <amit.kapila16@gmail.com>, Peter Smith <smithpb2250@gmail.com>, "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>, Masahiko Sawada <sawada.mshk@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>, shveta malik <shveta.malik@gmail.com>
Date: 2025-07-09T08:42:35Z
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

Please find a few more comments on July4 patch

6)
+  <para>
+   To synchronize sequences from a publisher to a subscriber, first publish
+   them using <link linkend="sql-createpublication-params-for-all-sequences">
+   <command>CREATE PUBLICATION ... FOR ALL SEQUENCES</command></link>.
+  </para>

This sentence looks odd, as we have 'first' but no follow-up sentence
after that. Can we please combine this line with the next one in the
doc saying:

To synchronize sequences from a publisher to a subscriber, first
publish them using CREATE PUBLICATION ... FOR ALL SEQUENCES and then
at the subscriber side:

7)

+         <para>
+          This parameter is not applicable for sequences.
+         </para>

It is mentioned 3 times in doc for publish, publish_generated_columns
and publish_via_partition_root. Instead shall we mention it once for
WITH-clause itself. Something like:

This clause specifies optional parameters for a publication when
publishing tables. This clause is not applicable for sequences.

8)
+   The view <structname>pg_publication_sequences</structname> provides
+   information about the mapping between publications and information of
+   sequences they contain.

Why not:
"The view pg_publication_sequences provides information about the
mapping between publications and sequences."

I think the existing detail has been written similar to
'pg_publication_tables' doc. But there, 'information of tables' made
sense as pg_publication_tables has attnames and rowfilters  too. But
pg_publication_sequences OTOH just has
the mapping between names. No other information.

9)
+  <sect2 id="sequence-definition-mismatches">
+   <title>Sequence Definition Mismatches</title>
+   <warning>
+    <para>
+     During sequence synchronization, the sequence definitions of the publisher
+     and the subscriber are compared.

Now in code, we give WARNING for missing sequences on publisher as
well. Do we need to mention that here? IIUC, this WARNING for missing
sequences can come only if the worker is respawned to sync
unmatched/failed sequences and meanwhile any one of failed sequences
is dropped on publisher. But it will be good to mention it briefly in
doc.


thanks
Shveta