Horton

Re: Logical Replication of sequences

Chao Li <li.evan.chao@gmail.com>

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From: Chao Li <li.evan.chao@gmail.com>
To: vignesh C <vignesh21@gmail.com>
Cc: Masahiko Sawada <sawada.mshk@gmail.com>, "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>, Nisha Moond <nisha.moond412@gmail.com>, shveta malik <shveta.malik@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: 2025-09-08T06:34:54Z
Lists: pgsql-hackers

Commits

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  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


> On Sep 8, 2025, at 14:00, vignesh C <vignesh21@gmail.com> wrote:
>> 
>> 
>> 1 - 0001
>> ```
>> diff --git a/src/test/regress/sql/sequence.sql b/src/test/regress/sql/sequence.sql
>> index 2c220b60749..c8adddbfa31 100644
>> --- a/src/test/regress/sql/sequence.sql
>> +++ b/src/test/regress/sql/sequence.sql
>> @@ -414,6 +414,6 @@ SELECT nextval('test_seq1');
>> SELECT nextval('test_seq1');
>> 
>> -- pg_get_sequence_data
>> -SELECT * FROM pg_get_sequence_data('test_seq1');
>> +SELECT last_value, is_called, log_cnt, page_lsn <= pg_current_wal_lsn() as lsn FROM pg_get_sequence_data('test_seq1');
>> 
>> DROP SEQUENCE test_seq1;
>> ```
>> 
>> As it shows log_cnt now, after calling pg_get_sequence_data(), I suggest add 8 nextval(), so that sequence goes to 11, and log_cnt should become to 22.
> 
> Could you please explain the reason you’d like this to be done?
> 


Because log_cnt is newly exposed, we want to verify its value in the test. When I first time ran the test code, I saw initial value of log_cnt was 32, then I thought log_cnt might get decreased if I ran nextval() again, but it didn’t. Only after I ran 10 (cache size) more nextval(), log_cnt got decreased by 10 to 22. The test code is a place for people to look for expected behavior. So I think adding more nextval() to verify and show the change of log_cnt is helpful.

Best regards,
--
Chao Li (Evan)
HighGo Software Co., Ltd.
https://www.highgo.com/