Re: Resetting spilled txn statistics in pg_stat_replication

On Thu, 8 Oct 2020 at 17:59, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>
> 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.
>

Agreed.

I've updated the patch. Please review it.

Regards,

--
Masahiko Sawada http://www.2ndQuadrant.com/
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