Re: Resetting spilled txn statistics in pg_stat_replication

On Thu, Oct 8, 2020 at 1:55 PM Masahiko Sawada
<masahiko(dot)sawada(at)2ndquadrant(dot)com> wrote:
>
> On Thu, 8 Oct 2020 at 14:10, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> >
> >
> > We can write if we want but there are few things we need to do for
> > that like maybe a new function like wait_for_spill_stats which will
> > check if the counters have become zero. Then probably call a reset
> > function, call a new wait function, and then again check stats to
> > ensure they are reset to 0.
>
> Yes.
>

I am not sure if it is worth but probably it is not a bad idea
especially if we extend the existing tests based on your below idea?

> > We can't write any advanced test which means reset the existing stats
> > perform some tests and again check stats because *slot_get_changes()
> > function can start from the previous WAL for which we have covered the
> > stats. We might write that if we can somehow track the WAL positions
> > from the previous test. I am not sure if we want to go there.
>
> Can we use pg_logical_slot_peek_changes() instead to decode the same
> transactions multiple times?
>

I think this will do the trick. If we want to go there then I suggest
we can have a separate regression test file in test_decoding with name
as decoding_stats, stats, or something like that. We can later add the
tests related to streaming stats in that file as well.

--
With Regards,
Amit Kapila.