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: 2025-05-27T10:29:45Z
Lists: pgsql-hackers 
On Mon, May 26, 2025 at 12:46 PM Zhijie Hou (Fujitsu)
<houzj.fnst@fujitsu.com> wrote:
>
> Attaching the V32 patch set which addressed comments in [1]~[5].

Thanks for the patch, I am still reviewing the patches, please find
few trivial comments for patch001:

1)

+ FullTransactionId last_phase_at; /* publisher transaction ID that must
+ * be awaited to complete before
+ * entering the final phase
+ * (RCI_WAIT_FOR_LOCAL_FLUSH) */

'last_phase_at' seems like we are talking about the phase in the past.
(similar to 'last' in last_recv_time).
Perhaps we should name it as 'final_phase_at'


2)
RetainConflictInfoData data = {0};

We can change this name as well to rci_data.

3)
+ /*
+ * Compute FullTransactionId for the oldest running transaction ID. This
+ * handles the case where transaction ID wraparound has occurred.
+ */
+ full_xid = FullTransactionIdFromAllowableAt(next_full_xid,
oldest_running_xid);

Shall we name it to full_oldest_xid for better clarity?


4)
+ /*
+ * Update and check the remote flush position if we are applying changes
+ * in a loop. This is done at most once per WalWriterDelay to avoid
+ * performing costy operations in get_flush_position() too frequently
+ * during change application.
+ */
+ if (last_flushpos < rci_data->remote_lsn && rci_data->last_recv_time &&
+ TimestampDifferenceExceeds(rci_data->flushpos_update_time,
+    rci_data->last_recv_time, WalWriterDelay))

a) costy --> costly

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.