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: "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.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>, Amit Kapila <amit.kapila16@gmail.com>
Date: 2024-12-02T11:43:32Z
Lists: pgsql-hackers 
On Friday, November 29, 2024 6:35 PM Kuroda, Hayato/黒田 隼人 <kuroda.hayato@fujitsu.com> wrote:
> 
> Dear Hou,
> 
> Thanks for updating the patch! Here are my comments mainly for 0001.

Thanks for the comments!

> 
> 02. maybe_advance_nonremovable_xid
> 
> ```
> +        case RCI_REQUEST_PUBLISHER_STATUS:
> +            request_publisher_status(data);
> +            break;
> ```
> 
> I think the part is not reachable because the transit
> RCI_REQUEST_PUBLISHER_STATUS->RCI_WAIT_FOR_PUBLISHER_STATU
> S is done in get_candidate_xid()->request_publisher_status().
> Can we remove this?

I changed to call the maybe_advance_nonremovable_xid() after changing the phase
in get_candidate_xid/wait_for_publisher_status, so that the code is reachable.

> 
> 
> 05. request_publisher_status
> 
> ```
> +    if (!reply_message)
> +    {
> +        MemoryContext oldctx = MemoryContextSwitchTo(ApplyContext);
> +
> +        reply_message = makeStringInfo();
> +        MemoryContextSwitchTo(oldctx);
> +    }
> +    else
> +        resetStringInfo(reply_message);
> ```
> 
> Same lines exist in two functions: can we provide an inline function?

I personally feel these codes may not worth a separate function since it’s simple.
So didn't change in this version.

> 
> 06. wait_for_publisher_status
> 
> ```
> +    if (!FullTransactionIdIsValid(data->last_phase_at))
> +        data->last_phase_at =
> FullTransactionIdFromEpochAndXid(data->remote_epoch,
> +
> + data->remote_nextxid);
> +
> ```
> 
> Not sure, is there a possibility that data->last_phase_at is valid here? It is
> initialized just before transiting to RCI_WAIT_FOR_PUBLISHER_STATUS.

Oh. I think last_phase_at should be initialized only in the first phase. Fixed.

Other comments look good to me and have been addressed in V13.

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.