Horton

Re: Conflict detection for update_deleted in logical replication

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.com>
To: Masahiko Sawada <sawada.mshk@gmail.com>
Cc: "Zhijie Hou (Fujitsu)" <houzj.fnst@fujitsu.com>, "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>, pgsql-hackers <pgsql-hackers@postgresql.org>, shveta malik <shveta.malik@gmail.com>, vignesh C <vignesh21@gmail.com>, Nisha Moond <nisha.moond412@gmail.com>, Dilip Kumar <dilipbalaut@gmail.com>
Date: 2025-07-22T03:48:51Z
Lists: pgsql-hackers 
On Mon, Jul 21, 2025 at 11:27 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:
>
> On Sun, Jul 20, 2025 at 9:00 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
> >
>
> > If so, I agree
> > with you, we don't need XIDs of other databases as logical WALSender
> > will anyway won't process transactions in other databases, so we can
> > exclude those. The function GetOldestActiveTransactionId() is called
> > from two places in patch get_candidate_xid() and
> > ProcessStandbyPSRequestMessage(). We don't need to care for XIDs in
> > other databases at both places but care for
> > Commit_Critical_Section_Phase when called from
> > ProcessStandbyPSRequestMessage(). So, we probably need two parameters
> > to distinguish those cases.
>
> Why do we need to include all XIDs even in the cases called from
> ProcessStandbyPSRequestMessage()?
>

No, we don't need all XIDs even in the case of
ProcessStandbyPSRequestMessage(). That is what I wrote: "The function
GetOldestActiveTransactionId() is called from two places in patch
get_candidate_xid() and ProcessStandbyPSRequestMessage(). We don't
need to care for XIDs in other databases at both places ...". Am I
missing something or you misread it?

> I guess that there is no chance that
> the changes happening on other (non-subscribed) databases could
> conflict with something on the subscriber.
>

Right.

-- 
With Regards,
Amit Kapila.

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.