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: Dilip Kumar <dilipbalaut@gmail.com>, Amit Kapila <amit.kapila16@gmail.com>
Cc: Nisha Moond <nisha.moond412@gmail.com>, Masahiko Sawada <sawada.mshk@gmail.com>, shveta malik <shveta.malik@gmail.com>, "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>, pgsql-hackers <pgsql-hackers@postgresql.org>, vignesh C <vignesh21@gmail.com>
Date: 2025-08-27T03:29:12Z
Lists: pgsql-hackers

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On Tuesday, August 26, 2025 5:02 PM Dilip Kumar <dilipbalaut@gmail.com> wrote:
> 
> On Tue, Aug 26, 2025 at 12:15 PM Amit Kapila <amit.kapila16@gmail.com>
> wrote:
> >
> > On Mon, Aug 25, 2025 at 5:05 PM Amit Kapila <amit.kapila16@gmail.com>
> wrote:
> > >
> 
> Some comments on latest patch

Thanks for the comments!

> 0001:
> 
> 1.
> +          <para>
> +           Note that setting a non-zero value for this option could lead to
> +           information for conflict detection being removed prematurely,
> +           potentially missing some conflict detections.
> +          </para>
> 
> We can improve this wording by saying "potentially incorrectly detecting some
> conflict"

I slightly reworded it to "potentially resulting in incorrect conflict detection."

> 
> 2.
> @@ -1175,6 +1198,8 @@ AlterSubscription(ParseState *pstate,
> AlterSubscriptionStmt *stmt,
>   bool update_failover = false;
>   bool update_two_phase = false;
>   bool check_pub_rdt = false;
> + bool ineffective_maxconflretention = false; bool update_maxretention =
> + false;
> 
> For making variable names more consistent, better to change
> 'ineffective_maxconflretention' to 'ineffective_maxretention' so that this will be
> more consistent with 'update_maxretention'
> 
> 3.
> +/*
> + * Report a NOTICE to inform users that max_conflict_retention_duration
> +is
> + * ineffective when retain_dead_tuples is disabled for a subscription.
> +An ERROR
> + * is not issued because setting max_conflict_retention_duration
> causes no harm,
> + * even when it is ineffective.
> + */
> +static void
> +notify_ineffective_max_retention(bool update_maxretention) {
> +ereport(NOTICE,  errcode(ERRCODE_INVALID_PARAMETER_VALUE),
> + update_maxretention
> + ? errmsg("max_conflict_retention_duration has no effect when
> retain_dead_tuples is disabled")
> + : errmsg("disabling retain_dead_tuples will render
> max_conflict_retention_duration ineffective"));  }
> 
> I really don't like to make a function for a single ereport, even if this is being
> called from multiple places.

I refactored this part based on some other comments, so these points
is addressed in the V66 patch set as well.

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.