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: "Zhijie Hou (Fujitsu)" <houzj.fnst@fujitsu.com>
Cc: shveta malik <shveta.malik@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: 2025-06-30T11:22:34Z
Lists: pgsql-hackers 
On Fri, Jun 27, 2025 at 7:58 AM Zhijie Hou (Fujitsu)
<houzj.fnst@fujitsu.com> wrote:
>
> Here is the V43 patch set which includes the following changes:
>

Few minor comments:
1.
@@ -29645,8 +29651,10 @@ postgres=# SELECT '0/0'::pg_lsn +
pd.segment_number * ps.setting::int + :offset
         Copies an existing logical replication slot
         named <parameter>src_slot_name</parameter> to a logical replication
         slot named <parameter>dst_slot_name</parameter>, optionally changing
-        the output plugin and persistence.  The copied logical slot starts
-        from the same <acronym>LSN</acronym> as the source logical slot.  Both
+        the output plugin and persistence.  The name cannot be
+        <literal>pg_conflict_detection</literal> as it is reserved for
+        the conflict detection.  The copied logical slot starts from the same
+        <acronym>LSN</acronym> as the source logical slot.  Both

/The name/The new slot name

2. The server version checks can be modified to 19000 as a new branch
is created now.

3.
This ensures that if the launcher loses track of the slot after
+   * a restart, it will remember to drop the slot when it is no longer
+   * requested by any subscription.

The link between the first part of the sentence before the comma is
not clear with the remaining part of the sentence. How about writing
it as: "Acquire the conflict detection slot at startup to ensure it
can be dropped if no longer needed after a restart."?

-- 
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.