Re: min_safe_lsn column in pg_replication_slots view

On Wed, Jul 01, 2020 at 11:14:21AM -0400, Alvaro Herrera wrote:
> On 2020-Jul-01, Amit Kapila wrote:
>> Okay, but do we think it is better to display this in
>> pg_replication_slots or some new view like pg_stat_*_slots as being
>> discussed in [1]? It should not happen that we later decide to move
>> this or similar stats to that view.
>
> It seems that the main motivation for having some counters in another
> view is the ability to reset them; and resetting this distance value
> makes no sense, so I think it's better to have it in
> pg_replication_slots.

pg_replication_slots would make sense to me than a stat view for a
distance column. Now, I have to admit that I am worried when seeing
design discussions on this thread for 13 after beta2 has been shipped,
so my vote would still be to remove for now the column in 13, document
an equivalent query to do this work (I actually just do that in a
bgworker monitoring repslot bloat now in some stuff I maintain
internally), and resend a patch in v14 to give the occasion for this
feature to go through one extra round of review. My 2c.
--
Michael