Horton

Re: Conflict detection for update_deleted in logical replication

Nisha Moond <nisha.moond412@gmail.com>

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From: Nisha Moond <nisha.moond412@gmail.com>
To: "Zhijie Hou (Fujitsu)" <houzj.fnst@fujitsu.com>
Cc: Amit Kapila <amit.kapila16@gmail.com>, Masahiko Sawada <sawada.mshk@gmail.com>, "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>, shveta malik <shveta.malik@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2025-01-22T10:04:27Z
Lists: pgsql-hackers 
On Sat, Jan 18, 2025 at 9:15 AM Zhijie Hou (Fujitsu)
<houzj.fnst@fujitsu.com> wrote:
>
>
> Here is the V24 patch set. I modified 0004 patch to implement the slot
> Invalidation part. Since the automatic recovery could be an optimization and
> the discussion is in progress, I didn't implement that part.

Few comments for patch-0004
====
src/backend/replication/slot.c

1) Need to describe the new macro RS_INVAL_CONFLICT_RETENTION_DURATION
in the comments above InvalidateObsoleteReplicationSlots(), where all
other invalidation causes are explained.
...
 * Whether a slot needs to be invalidated depends on the cause. A slot is
 * removed if it:
 * - RS_INVAL_WAL_REMOVED: requires a LSN older than the given segment
 * - RS_INVAL_HORIZON: requires a snapshot <= the given horizon in the given
 *   db; dboid may be InvalidOid for shared relations
 * - RS_INVAL_WAL_LEVEL: is logical
...

2) Can we mention the GUC parameter that defines this "maximum limit"
while reporting?

+
+ case RS_INVAL_CONFLICT_RETENTION_DURATION:
+ appendStringInfo(&err_detail, _("The duration for retaining conflict
information exceeds the maximum limit."));
+ break;
+

Something like -
  "The duration for retaining conflict information exceeds the maximum
limit configured in \"%s\".","max_conflict_retention_duration"

=====
doc/src/sgml/ref/create_subscription.sgml

3)
+         <para>
+          Note that setting a non-zero value for this option could lead to
+          conflict information being removed prematurely, potentially missing
+          some conflict detections.
+         </para>

Should we add the above info as a “Warning” in the docs?

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.