Horton

Re: Conflict detection for update_deleted in logical replication

shveta malik <shveta.malik@gmail.com>

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From: shveta malik <shveta.malik@gmail.com>
To: "Zhijie Hou (Fujitsu)" <houzj.fnst@fujitsu.com>
Cc: Amit Kapila <amit.kapila16@gmail.com>, "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>, pgsql-hackers <pgsql-hackers@postgresql.org>, vignesh C <vignesh21@gmail.com>, Nisha Moond <nisha.moond412@gmail.com>, Dilip Kumar <dilipbalaut@gmail.com>, Masahiko Sawada <sawada.mshk@gmail.com>, shveta malik <shveta.malik@gmail.com>
Date: 2025-08-01T03:44:05Z
Lists: pgsql-hackers 
On Thu, Jul 31, 2025 at 3:49 PM Zhijie Hou (Fujitsu)
<houzj.fnst@fujitsu.com> wrote:
>
> On Thursday, July 31, 2025 5:26 PM shveta malik <shveta.malik@gmail.com> wrote:
> >
> > On Tue, Jul 29, 2025 at 10:51 AM Zhijie Hou (Fujitsu) <houzj.fnst@fujitsu.com>
> > wrote:
> > >
> > >
> > > This is the V54 patch set, with only patch 0001 updated to address the
> > > latest comments.
> > >
> >
> > Thanks for the patch.
> >
> > While performing tests on the latest patch, I found an assert in tablesync
> > worker in FindDeletedTupleInLocalRel (see
> > Assert(TransactionIdIsValid(oldestxmin))). Logs at [1].
> >
> > It seems table sync worker is trying to apply changes and going to
> > update-deleted conflict detection patch but is not able to find
> > MyLogicalRepWorker->oldest_nonremovable_xid as this xid is set only
> > for apply-worker.
>
> Thanks for reporting. I have fixed it by referring to conflict detection slot's
> xmin instead of the leader worker's oldest_nonremovable_xid. This should
> be safe because the slot.xmin is always valid.
>

Thanks for fixing. In the same context, the comment below still
mentions oldest_nonremovable_xid, it can be corrected.

+  /*
+   * No need to check for a frozen transaction ID, as
+   * TransactionIdPrecedes() manages it internally, treating it as falling
+   * behind the oldest_nonremovable_xid.
+   */

~

Also we may mention 'concurrently deleted' in the comment below as
that makes more sense.

/* The row to be updated was deleted by a different origin */
  CT_UPDATE_DELETED,

~

Apart from these trivial comments changes, patch001 and patch002 look
good to me.

thanks
Shveta

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.