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>, Nisha Moond <nisha.moond412@gmail.com>, Masahiko Sawada <sawada.mshk@gmail.com>, "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>, pgsql-hackers <pgsql-hackers@postgresql.org>, vignesh C <vignesh21@gmail.com>, Dilip Kumar <dilipbalaut@gmail.com>, shveta malik <shveta.malik@gmail.com>
Date: 2025-09-03T04:19:21Z
Lists: pgsql-hackers 
On Tue, Sep 2, 2025 at 3:30 PM shveta malik <shveta.malik@gmail.com> wrote:
>
> >
> > >
> > > Here is V70 patch set.
> > >
> >

Please find a few comments on v70-003:

1)
Doc of dead_tuple_retention_active says:
True if retain_dead_tuples is enabled and the retention duration for
information used in conflict detection is within
max_retention_duration

Doc of subretentionactive says:
The retention status of information (e.g., dead tuples, commit
timestamps, and origins) useful for conflict detection. True if
retain_dead_tuples is enabled, and the retention duration has not
exceeded max_retention_duration, when defined.

There is hardly any difference between the two. Do we really need to
have 'dead_tuple_retention_active' when we already have
'subretentionactive'?

2)
Doc wise, there is no difference between the two, but there is a small
window when sub's subretentionactive will show true while stat's
dead_tuple_retention_active will show false. This will be when worker
is waiting for the launcher to assign its oldest-xid after it has
marked itself as 'resuming'.
If we decide to retain 'dead_tuple_retention_active', then do we need
to indicate the small difference between the 2 fields in the doc?

3)
We can add a test when we stop-retention to see if this is showing
false. Currently there are 2 places in the test where we check this
field to see if it is true. I think we can shift both in the same
test. One check before stop-retention, one check after stop-retention.

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.