Re: Failed transaction statistics to measure the logical replication progress

On Thu, Oct 14, 2021 at 9:23 AM houzj(dot)fnst(at)fujitsu(dot)com
<houzj(dot)fnst(at)fujitsu(dot)com> wrote:
>
> On Thursday, September 30, 2021 12:15 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
> >
> > These all views are related to untransmitted to the collector but what
> > we really need is a view similar to pg_stat_archiver or
> > pg_stat_bgwriter which gives information about background workers.
> > Now, the problem as I see is if we go that route then
> > pg_stat_subscription will no longer remain dynamic view and one might
> > consider that as a compatibility break. The other idea I have shared
> > is that we display these stats under the new view introduced by
> > Sawada-San's patch [1] and probably rename that view as
> > pg_stat_subscription_worker where all the stats (xact info and last
> > failure information) about each worker will be displayed. Do you have
> > any opinion on that idea or do you see any problem with it?
>
> Personally, I think it seems reasonable to merge the xact stat into the view from
> sawada-san's patch.
>
> One problem I noticed is that pg_stat_subscription_error
> currently have a 'count' column which show how many times the last error
> happened. The xact stat here also have a similar value 'xact_error'. I think we
> might need to rename it or merge them into one in some way.
>
> Besides, if we decide to merge xact stat into pg_stat_subscription_error, some column
> seems need to be renamed. Maybe like:
> error_message => Last_error_message, command=> last_error_command..
>

Don't you think that keeping the view name as
pg_stat_subscription_error would be a bit confusing if it has to
display xact_info? Isn't it better to change it to
pg_stat_subscription_worker or some other worker-specific generic
name?

--
With Regards,
Amit Kapila.