Horton

Re: Conflict detection for update_deleted in logical replication

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.com>
To: "Zhijie Hou (Fujitsu)" <houzj.fnst@fujitsu.com>
Cc: "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.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: 2025-01-07T08:49:37Z
Lists: pgsql-hackers 
On Fri, Jan 3, 2025 at 11:22 AM Amit Kapila <amit.kapila16@gmail.com> wrote:
>
> 5.
> +
> +      <varlistentry
> id="sql-createsubscription-params-with-detect-update-deleted">
> +        <term><literal>detect_update_deleted</literal>
> (<type>boolean</type>)</term>
> +        <listitem>
> +         <para>
> +          Specifies whether the detection of <xref
> linkend="conflict-update-deleted"/>
> +          is enabled. The default is <literal>false</literal>. If set to
> +          true, the dead tuples on the subscriber that are still useful for
> +          detecting <xref linkend="conflict-update-deleted"/>
> +          are retained,
>
> One of the purposes of retaining dead tuples is to detect
> update_delete conflict. But, I also see the following in 0001's commit
> message: "Since the mechanism relies on a single replication slot, it
> not only assists in retaining dead tuples but also preserves commit
> timestamps and origin data. These information will be displayed in the
> additional logs generated for logical replication conflicts.
> Furthermore, the preserved commit timestamps and origin data are
> essential for consistently detecting update_origin_differs conflicts."
> which indicates there are other cases where retaining dead tuples can
> help. So, I was thinking about whether to name this new option as
> retain_dead_tuples or something along those lines?
>

The other possible option name could be retain_conflict_info.
Sawada-San, and others, do you have any preference for the name of
this option?

-- 
With Regards,
Amit Kapila.

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.