Horton

RE: Conflict detection for update_deleted in logical replication

Zhijie Hou (Fujitsu) <houzj.fnst@fujitsu.com>

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From: "Zhijie Hou (Fujitsu)" <houzj.fnst@fujitsu.com>
To: vignesh C <vignesh21@gmail.com>
Cc: "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>, Amit Kapila <amit.kapila16@gmail.com>, 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: 2025-01-07T12:34:23Z
Lists: pgsql-hackers 
On Thursday, January 2, 2025 6:34 PM vignesh C <vignesh21@gmail.com> wrote:
> 
> Few suggestions:
> 1) If we have a subscription with detect_update_deleted option and we
> try to upgrade it with default settings(in case dba forgot to set
> track_commit_timestamp), the upgrade will fail after doing a lot of
> steps like that mentioned in ok below:
> Setting locale and encoding for new cluster                   ok
> Analyzing all rows in the new cluster                         ok
> Freezing all rows in the new cluster                          ok
> Deleting files from new pg_xact                               ok
> Copying old pg_xact to new server                             ok
> Setting oldest XID for new cluster                            ok
> Setting next transaction ID and epoch for new cluster         ok
> Deleting files from new pg_multixact/offsets                  ok
> Copying old pg_multixact/offsets to new server                ok
> Deleting files from new pg_multixact/members                  ok
> Copying old pg_multixact/members to new server                ok
> Setting next multixact ID and offset for new cluster          ok
> Resetting WAL archives                                        ok
> Setting frozenxid and minmxid counters in new cluster         ok
> Restoring global objects in the new cluster                   ok
> Restoring database schemas in the new cluster
>   postgres
> *failure*
> 
> We should detect this at an earlier point somewhere like in
> check_new_cluster_subscription_configuration and throw an error from
> there.
> 
> 2) Also should we include an additional slot for the
> pg_conflict_detection slot while checking max_replication_slots.
> Though this error will occur after the upgrade is completed, it may be
> better to include the slot during upgrade itself so that the DBA need
> not handle this error separately after the upgrade is completed.

Thanks for the comments!

I added the suggested changes but didn't add more tests to verify each error
message in this version, because it seems a rare case to me, so I am not sure
if it's worth increasing the testing time for these errors. But I am OK to add
if people think it's worth the effort and I will also test this locally.

Best Regards,
Hou zj

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.