Re: Extend documentation for pg_stat_replication.backend_xmin

On Thu, Oct 16, 2025 at 8:07 AM Renzo Dani <arons7@gmail.com> wrote:

> Really nice,
> Thanks a lot for the info and review.
> Taken into the patch.
>
> Regards,
> Renzo Dani
>
> On Thu, Oct 16, 2025 at 5:32 AM Fujii Masao <masao.fujii@gmail.com> wrote:
>
>> On Thu, Oct 16, 2025 at 12:47 AM Renzo Dani <arons7@gmail.com> wrote:
>> >
>> > Hi,
>> > recently I had some issue understanding what was going on with a
>> replica and the reported xmin.
>> > I have than created a patch to better specify the value expected into
>> the pg_stat_replication.backend_xmin field.
>>
>> +1
>>
>> +       This field will be null if a replication slot is used; in that
>> case, the xmin is available through <link
>> linkend="view-pg-replication-slots">pg_replication_slots</link>.
>>
>> I think it would be better to also mention that this field is null
>> when hot_standby_feedback is disabled.
>>
>> Also, <literal> tags should be used for "xmin", and a newline should
>> be added to avoid an overly long line.
>>
>> Based on the above comments, how about revising it as follows?
>>
>> +       This field will be null if a replication slot is used (in this
>> case,
>> +       the standby's <literal>xmin</literal> is shown in
>> +       <link
>> linkend="view-pg-replication-slots">pg_replication_slots</link>)
>> +       or if <varname>hot_standby_feedback</varname> is disabled.
>>
>> Regards,
>>
>> --
>> Fujii Masao
>>
>
I think I did it the wrong way with the patches.
So here again with all in one file.
Sorry for that.

Regards
Renzo