Horton

RE: Conflict detection for update_deleted in logical replication

Zhijie Hou (Fujitsu) <houzj.fnst@fujitsu.com>

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From: "Zhijie Hou (Fujitsu)" <houzj.fnst@fujitsu.com>
To: shveta malik <shveta.malik@gmail.com>
Cc: Amit Kapila <amit.kapila16@gmail.com>, vignesh C <vignesh21@gmail.com>, Masahiko Sawada <sawada.mshk@gmail.com>, Nisha Moond <nisha.moond412@gmail.com>, "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2025-06-27T02:28:10Z
Lists: pgsql-hackers

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On Thu, Jun 26, 2025 at 4:28 PM shveta malik wrote:
> 
> On Thu, Jun 26, 2025 at 8:31 AM Zhijie Hou (Fujitsu)
> <houzj.fnst@fujitsu.com> wrote:
> >
> > Thanks for the comments. All of them look good to me and
> > have been addressed in V42.
> >
> 
> Thank You for the patches. Few comments.
> 
> t/035_conflicts.pl:
> 
> 1)
> Both the subscriptions subname_BA and subname_AB have rci enabled
> during CREATE sub itself. And later in the second test, we are trying
> to enable rci of subname_AB  to test WARNING and NOTICE, but rci is
> already enabled. Shall we have one CREATE sub with rci enabled while
> another CREATE sub with default rci. And then we try to enable rci of
> the second sub later and check pg_conflict_detection slot has been
> created once we enabled rci. This way, it will cover more scenarios.

Agreed and changed as suggested. I removed the test for WARNING since the
message is the same as the NOITCE and it seems not worthwhile to disable
the subscription again to verify one message.

> 
> 2)
> +$node_B->safe_psql('postgres', "UPDATE tab SET b = 3 WHERE a = 1;");
> +$node_A->safe_psql('postgres', "DELETE FROM tab WHERE a = 1;");
> +
> +$node_A->wait_for_catchup($subname_BA);
> 
> Can you please help me understand why we are doing  wait_for_catchup
> here? Do we want DELETE to be replicated from A to B? IMO, this step
> is not essential for our test as we have node_A->poll_query  until
> xmin = $next_xid in pg_conflict_detection and that should suffice to
> ensure both DELETE and UPDATE are replicated from one to other.

I think this step belongs to a later patch to ensure the DELETE operation is
replicated to Node B, allowing us to verify the `delete_origin_differ`
conflicts detected there. So, I moved it to the later patches.

Here is the V43 patch set which includes the following changes:

0001:
* Addressed the comments above.

0002:
No change.

0003:
No change.

0004:
* Moved some tests from 0001 to here.

0005:
No change.


Best Regards,
Hou zj

Commits

  1. Fix intermittent BF failures in 035_conflicts.

  2. Resume conflict-relevant data retention automatically.

  3. Fix intermittent test failure introduced in 6456c6e2c4.

  4. Fix Coverity issue reported in commit a850be2fe.

  5. Add test to prevent premature removal of conflict-relevant data.

  6. Post-commit review fixes for 228c370868.

  7. Add max_retention_duration option to subscriptions.

  8. Detect and report update_deleted conflicts.

  9. Preserve conflict-relevant data during logical replication.

  10. Integrate FullTransactionIds deeper into two-phase code

  11. Improve checks for GUC recovery_target_timeline

  12. Prevent excessive delays before launching new logrep workers.

  13. Keep WAL segments by slot's last saved restart LSN

  14. Rework some code handling pg_subscription data in psql and pg_dump

  15. Use generateClonedIndexStmt to propagate CREATE INDEX to partitions.