Re: Failed transaction statistics to measure the logical replication progress

On Tue, Sep 28, 2021 at 8:04 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>
> > Another idea could be to have a separate
> > view, say pg_stat_subscription_xact but I'm not sure it's a better
> > idea.
> >
>
> Yeah, that is another idea but I am afraid that having three different
> views for subscription stats will be too much. I think it would be
> better if we can display these additional stats via the existing view
> pg_stat_subscription or the new view pg_stat_subscription_errors (or
> whatever name we want to give it).
>

It seems that we have come full-circle in the discussion of how these
new stats could be best added.
Other than adding a new "pg_stats_subscription_xact" view (which Amit
thought would result in too many views) I don't see any clear solution
here, because the new xact-related cumulative stats don't really
consistently integrate with the existing in-memory stats in
pg_stat_subscription, and IMHO the new stats wouldn't integrate well
into the existing error-related stats in the
"pg_stat_subscription_errors" view (even if its name was changed, that
view in any case maintains lowel-level error details and the way error
entries are removed doesn't allow the "success" stats to be maintained
for the subscription and doesn't fit well with the added
"pg_stat_reset_subscription_error" function either).
If we can't really add another view like "pg_stats_subscription_xact",
it seems we need to find some way the new stats fit more consistently
into the existing "pg_stat_subscription" view.

Regards,
Greg Nancarrow
Fujitsu Australia