Horton

RE: Conflict detection for update_deleted in logical replication

Hayato Kuroda (Fujitsu) <kuroda.hayato@fujitsu.com>

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From: "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>
To: "Zhijie Hou (Fujitsu)" <houzj.fnst@fujitsu.com>, Amit Kapila <amit.kapila16@gmail.com>
Cc: 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: 2024-12-23T06:14:49Z
Lists: pgsql-hackers 
Dear Hou,

Thanks for updating the patch. Few comments:

01. worker.c

```
+/*
+ * The minimum (100ms) and maximum (3 minutes) intervals for advancing
+ * non-removable transaction IDs.
+ */
+#define MIN_XID_ADVANCEMENT_INTERVAL 100
+#define MAX_XID_ADVANCEMENT_INTERVAL 180000L
```

Since the max_interval is an integer variable, it can be s/180000L/180000/.


02.  ErrorOnReservedSlotName()

Currently the function is callsed from three points - create_physical_replication_slot(),
create_logical_replication_slot() and CreateReplicationSlot(). 
Can we move them to the ReplicationSlotCreate(), or combine into ReplicationSlotValidateName()?

03. advance_conflict_slot_xmin()

```
	Assert(TransactionIdIsValid(MyReplicationSlot->data.xmin));
```

Assuming the case that the launcher crashed just after ReplicationSlotCreate(CONFLICT_DETECTION_SLOT).
After the restart, the slot can be acquired since SearchNamedReplicationSlot(CONFLICT_DETECTION_SLOT)
is true, but the process would fail the assert because data.xmin is still invalid.

I think we should re-create the slot when the xmin is invalid. Thought?

04. documentation

Should we update "Configuration Settings" section in logical-replication.sgml
because an additional slot is required?

05. check_remote_recovery()

Can we add a test case related with this?

Best regards,
Hayato Kuroda
FUJITSU LIMITED

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.