Re: Logical Replication of sequences

Nisha Moond <nisha.moond412@gmail.com>

From: Nisha Moond <nisha.moond412@gmail.com>

To: vignesh C <vignesh21@gmail.com>

Cc: shveta malik <shveta.malik@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>, Amit Kapila <amit.kapila16@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: 2025-05-28T15:21:52Z

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 →

Doc: Add documentation for sequence synchronization.
- 55cefadde874 19 (unreleased) landed
Remove unused assignment in CREATE PUBLICATION grammar.
- bfb7419b0bbe 19 (unreleased) landed
Add seq_sync_error_count to subscription statistics.
- f6a4c498dcf6 19 (unreleased) landed
Fix few issues in commit 5509055d69.
- 5a4eba558aa7 19 (unreleased) landed
Add sequence synchronization for logical replication.
- 5509055d6956 19 (unreleased) landed
Add worker type argument to logical replication worker functions.
- 3e8e05596a02 19 (unreleased) landed
Introduce "REFRESH SEQUENCES" for subscriptions.
- f0b3573c3aac 19 (unreleased) landed
Refactor logical worker synchronization code into a separate file.
- 41c674d2e31e 19 (unreleased) landed
Standardize use of REFRESH PUBLICATION in code and messages.
- 2436b8c047ff 19 (unreleased) landed
Add "ALL SEQUENCES" support to publications.
- 96b378497346 19 (unreleased) landed
Expose sequence page LSN via pg_get_sequence_data.
- b93172ca59f4 19 (unreleased) landed
Resume conflict-relevant data retention automatically.
- 0d48d393d465 19 (unreleased) cited
Post-commit review fixes for 228c370868.
- 1f7e9ba3ac4e 19 (unreleased) cited
Generate GUC tables from .dat file
- 63599896545c 19 (unreleased) cited

On Thu, May 22, 2025 at 10:42 PM vignesh C <vignesh21@gmail.com> wrote:
>
>
> The attached v20250522 patch has the changes for the same.
>

Thank you for the patches, please find comments for patch-0004.

1)
+/*
+ * report_error_sequences
+ *
+ * Logs a warning listing all sequences that are missing on the publisher,
+ * as well as those with value mismatches relative to the subscriber.
+ */
+static void
+report_error_sequences(StringInfo missing_seqs, StringInfo mismatched_seqs)

The function description should be updated to reflect the recent
changes, as it now raises an error instead of issuing a warning.

2)
+ ereport(ERROR, errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("%s", combined_error_msg->data));
+
+ destroyStringInfo(combined_error_msg);
+}

I think we can remove destroyStringInfo() as we will never reach here
in case of error.

3)
+ * we want to avoid keeping this batch transaction open for extended
+ * periods so it iscurrently limited to 100 sequences per batch.
+ */

typo :  iscurrently / is currently

4)
+ HeapTuple tup;
+ Form_pg_sequence seqform;
+ LogicalRepSequenceInfo *seqinfo;
+
[...]
+ Assert(seqinfo);

Since there's an assertion for 'seqinfo', it would be safer to
initialize it to NULL to avoid any unexpected behavior.

6)
+ if (missing_seqs->len || mismatched_seqs->len)
+ report_error_sequences(missing_seqs, mismatched_seqs);

I think it would be helpful to add a comment for this check, perhaps
something like:
/*
 * Report an error if any sequences are missing on the remote side
 * or if local sequence parameters don't match with the remote ones.
 */
 Please rephrase if needed.
~~~~

--
Thanks,
Nisha