Horton

Re: Conflict detection for update_deleted in logical replication

Michail Nikolaev <michail.nikolaev@gmail.com>

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From: Michail Nikolaev <michail.nikolaev@gmail.com>
To: "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>
Cc: "Zhijie Hou (Fujitsu)" <houzj.fnst@fujitsu.com>, Amit Kapila <amit.kapila16@gmail.com>, Masahiko Sawada <sawada.mshk@gmail.com>, shveta malik <shveta.malik@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>, Peter Smith <smithpb2250@gmail.com>, Nisha Moond <nisha.moond412@gmail.com>
Date: 2024-10-30T11:31:29Z
Lists: pgsql-hackers 
Hello Hayato!

> Note that apply workers can stop due to some reasons (e.g., disabling
subscriptions,
> error out, deadlock...). In this case, the snapshot cannot eb registered
by the
> worker and index can be re-built during the period.

However, the xmin of a slot affects replication_slot_xmin in
ProcArrayStruct, so it might
be straightforward to wait for it during concurrent index builds. We could
consider adding
a separate conflict_resolution_replication_slot_xmin to wait only for that.

> Anyway, this topic introduces huge complexity and is not mandatory for
update_deleted
> detection. We can work on it in later versions based on the needs.

From my perspective, this is critical for databases. REINDEX CONCURRENTLY
is typically run
in production databases on regular basic, so any master-master system
should be unaffected by it.

Best regards,
Mikhail.

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.