Re: Conflict detection for update_deleted in logical replication

On Fri, Jan 3, 2025 at 11:22 AM Amit Kapila <amit(dot)kapila16(at)gmail(dot)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.