Re: [PATCH] Use indexes on the subscriber when REPLICA IDENTITY is full on the publisher

On Sat, Mar 11, 2023 at 6:05 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
>
> On Fri, Mar 10, 2023 at 7:58 PM Önder Kalacı <onderkalaci@gmail.com> wrote:
> >
> >
> > I think one option could be to drop some cases altogether, but not sure we'd want that.
> >
> > As a semi-related question: Are you aware of any setting that'd make pg_stat_all_indexes
> > reflect the changes sooner? It is hard to debug what is the bottleneck in the tests, but
> > I have a suspicion that there might be several poll_query_until() calls on
> > pg_stat_all_indexes, which might be the reason?
> >
>
> Yeah, I also think poll_query_until() calls on pg_stat_all_indexes is
> the main reason for these tests taking more time. When I commented
> those polls, it drastically reduces the test time. On looking at
> pgstat_report_stat(), it seems we don't report stats sooner than 1s
> and as most of this patch's test relies on stats, it leads to taking
> more time. I don't have a better idea to verify this patch without
> checking whether the index scan is really used by referring to
> pg_stat_all_indexes. I think trying to reduce the poll calls may help
> in reducing the test timings further. Some ideas on those lines are as
> follows:

If the reason for the stats polling was only to know if some index is
chosen or not, I was wondering if you can just convey the same
information to the TAP test via some conveniently placed (DEBUG?)
logging.

This way the TAP test can do a 'wait_for_log' instead of the
'poll_query_until'. It will probably generate lots of extra logging
but it still might be lots faster that current code because it won't
incur the 1s overheads of the stats.

------
Kind Regards,
Peter Smith.
Fujitsu Australia.