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: Peter Smith <smithpb2250@gmail.com>, Shlok Kyal <shlok.kyal.oss@gmail.com>, Amit Kapila <amit.kapila16@gmail.com>, Masahiko Sawada <sawada.mshk@gmail.com>, Peter Eisentraut <peter@eisentraut.org>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Tomas Vondra <tomas.vondra@enterprisedb.com>, Euler Taveira <euler@eulerto.com>, Michael Paquier <michael@paquier.xyz>, "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>, Hou, Zhijie/侯 志杰 <houzj.fnst@fujitsu.com>, "Jonathan S. Katz" <jkatz@postgresql.org>, shveta malik <shveta.malik@gmail.com>
Date: 2024-07-25T06:38:19Z
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

On Thu, Jul 25, 2024 at 9:06 AM vignesh C <vignesh21@gmail.com> wrote:
>
> The attached v20240725 version patch has the changes for the same.

Thank You for addressing the comments. Please review below issues:

1) Sub ahead of pub due to wrong initial sync of last_value for
non-incremented sequences. Steps at [1]
2) Sequence's min value is not honored on sub during replication. Steps at [2]

[1]:
-----------
on PUB:
CREATE SEQUENCE myseq001 INCREMENT 5 START 100;
SELECT * from pg_sequences; -->shows last_val as NULL

on SUB:
CREATE SEQUENCE myseq001 INCREMENT 5 START 100;
SELECT * from pg_sequences; -->correctly shows last_val as NULL
ALTER SUBSCRIPTION sub1 REFRESH PUBLICATION SEQUENCES;
SELECT * from pg_sequences;  -->wrongly updates last_val to 100; it is
still NULL on Pub.

Thus , SELECT nextval('myseq001') on pub gives 100, while on sub gives 105.
-----------


[2]:
-----------
Pub:
CREATE SEQUENCE myseq0 INCREMENT 5 START 10;
SELECT * from pg_sequences;

Sub:
CREATE SEQUENCE myseq0 INCREMENT 5 MINVALUE 100;

Pub:
SELECT nextval('myseq0');
SELECT nextval('myseq0');

Sub:
ALTER SUBSCRIPTION sub1 REFRESH PUBLICATION SEQUENCES;
--check 'last_value', it is 15 while min_value is 100
SELECT * from pg_sequences;
-----------

thanks
Shveta