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: Dilip Kumar <dilipbalaut@gmail.com>
Cc: vignesh C <vignesh21@gmail.com>, "Zhijie Hou (Fujitsu)" <houzj.fnst@fujitsu.com>, "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>, Nisha Moond <nisha.moond412@gmail.com>, Masahiko Sawada <sawada.mshk@gmail.com>, shveta malik <shveta.malik@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2025-01-16T10:31:47Z
Lists: pgsql-hackers 
On Thu, Jan 16, 2025 at 3:45 PM Dilip Kumar <dilipbalaut@gmail.com> wrote:
>
> On Fri, Jan 3, 2025 at 4:31 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
>>
>> On Thu, Jan 2, 2025 at 2:57 PM vignesh C <vignesh21@gmail.com> wrote:
>> >
>> > Conflict detection of truncated updates is detected as update_missing
>> > and deleted update is detected as update_deleted. I was not sure if
>> > truncated updates should also be detected as update_deleted, as the
>> > document says truncate operation is "It has the same effect as an
>> > unqualified DELETE on each table" at [1].
>> >
>>
>> This is expected behavior because TRUNCATE would immediately reclaim
>> space and remove all the data. So, there is no way to retain the
>> removed row.
>
>
> I’m not sure whether to call this expected behavior or simply acknowledge that we have no way to control it. Logically, it would have been preferable if it behaved like a DELETE, but we are constrained by the way TRUNCATE works.
>

I see your point. So, it is probably better to add a Note about this.

-- 
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.