Re: Logical Replication of sequences

Peter Smith <smithpb2250@gmail.com>

From: Peter Smith <smithpb2250@gmail.com>

To: vignesh C <vignesh21@gmail.com>

Cc: "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>, Masahiko Sawada <sawada.mshk@gmail.com>, shveta malik <shveta.malik@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: 2025-04-23T23:36:57Z

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

Hi Vignesh,

Some review comments for patch v20250422-0003.

======
src/backend/replication/logical/syncutils.c

1.
+/*
+ * Exit routine for synchronization worker.
+ */
+pg_noreturn void
+SyncFinishWorker(void)

Why does this have the pg_noreturn annotation? None of the other void
functions do.

~~~

2.
+bool
+FetchRelationStates(bool *started_tx)

All the functions in the sync utils.c are named like Syncxxx, so for
consistency, why not name this one also?
e.g. /FetchRelationStates/SyncFetchRelationStates/

======
src/backend/replication/logical/tablesync.c

3.
-static bool
-wait_for_relation_state_change(Oid relid, char expected_state)
+bool
+WaitForRelationStateChange(Oid relid, char expected_state)
 {
  char state;
~

3a.
Why isn't this static, like before?

~

3b.
If it is *only* for tables and nothing else, shouldn't it be static
and have a function name like 'wait_for_table_state_change' (not
_relation_)?
OTOH, if there is potential for this to be used for sequences in
future, then it should be in the syncutils.c module with a name like
'SyncWaitForRelationStateChange'.

======
src/include/replication/worker_internal.h

4.
@@ -250,6 +252,7 @@ extern void logicalrep_worker_stop(Oid subid, Oid relid);
 extern void logicalrep_pa_worker_stop(ParallelApplyWorkerInfo *winfo);
 extern void logicalrep_worker_wakeup(Oid subid, Oid relid);
 extern void logicalrep_worker_wakeup_ptr(LogicalRepWorker *worker);
+pg_noreturn extern void SyncFinishWorker(void);

 extern int logicalrep_sync_worker_count(Oid subid);

@@ -259,9 +262,13 @@ extern void
ReplicationOriginNameForLogicalRep(Oid suboid, Oid relid,
 extern bool AllTablesyncsReady(void);
 extern void UpdateTwoPhaseState(Oid suboid, char new_state);

-extern void process_syncing_tables(XLogRecPtr current_lsn);
-extern void invalidate_syncing_table_states(Datum arg, int cacheid,
- uint32 hashvalue);
+extern bool FetchRelationStates(bool *started_tx);
+extern bool WaitForRelationStateChange(Oid relid, char expected_state);
+extern void ProcessSyncingTablesForSync(XLogRecPtr current_lsn);
+extern void ProcessSyncingTablesForApply(XLogRecPtr current_lsn);
+extern void SyncProcessRelations(XLogRecPtr current_lsn);
+extern void SyncInvalidateRelationStates(Datum arg, int cacheid,
+ uint32 hashvalue);

~

4a.
Why does SyncFinishWorker have the pg_noreturn annotation? None of the
other void functions do.

~

4b.
I felt that all the SyncXXX functions exposed from syncutils.c should
be grouped together, and maybe even with a comment like /* from
syncutils.c */

======
Kind Regards,
Peter Smith.
Fujitsu Australia