Horton

Re: Conflict detection for update_deleted in logical replication

shveta malik <shveta.malik@gmail.com>

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From: shveta malik <shveta.malik@gmail.com>
To: "Zhijie Hou (Fujitsu)" <houzj.fnst@fujitsu.com>
Cc: Amit Kapila <amit.kapila16@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>, shveta malik <shveta.malik@gmail.com>
Date: 2025-06-24T10:20:54Z
Lists: pgsql-hackers 
On Mon, Jun 23, 2025 at 4:20 PM Zhijie Hou (Fujitsu)
<houzj.fnst@fujitsu.com> wrote:
>
>
> Here is the V40 patch set

Thanks for the patches. Few comments:

1)
In get_subscription_info(), we are doing COUNT of rci-subscriptions
using below query:
SELECT count(*) AS nsub, COUNT(CASE WHEN subretainconflictinfo THEN 1
END) AS retain_conflict_info FROM pg_catalog.pg_subscription;

And then we are doing:
cluster->sub_retain_conflict_info = (strcmp(PQgetvalue(res, 0,
i_retain_conflict_info), "1") == 0);

i.e. get the value and compare with "1".  If the count of such subs is
say 2, won't it fail and will set sub_retain_conflict_info as 0?

2)
create_logical_replication_slots(void)
{
+ if (!count_old_cluster_logical_slots())
+ return;
+

We shall get rid of count_old_cluster_logical_slots() here as the
caller is checking it already.

3)
We can move the 'old_cluster.sub_retain_conflict_info' check from
create_conflict_detection_slot() to its caller. Then it will be more
informative and consistent with how we check migrate_logical_slots
outside of create_conflict_detection_slot()

thanks
Shveta

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.