Re: Introduce a new view for checkpointer related stats

On Mon, Oct 30, 2023 at 6:19 AM Michael Paquier <michael@paquier.xyz> wrote:
>
> On Fri, Oct 27, 2023 at 10:23:34AM +0530, Bharath Rupireddy wrote:
> > +1. Changed in the attached v10-001. FWIW, having a test case in
> > stats.sql emitting this error message and hint would have helped here.
> > If okay, I can add one.
>
> That may be something to do.  At least it was missed on this thread,
> even if we don't add a new  pgstat shared type every day.

Right. Adding test coverage for the error-case is no bad IMV
(https://coverage.postgresql.org/src/backend/utils/adt/pgstatfuncs.c.gcov.html).
Here's the attached 0001 patch for that.

> > PS: I'll park the SLRU flush related patch aside until the approach is
> > finalized. I'm posting the pg_stat_checkpointer patch as v10-0001.
>
> +-- Test that reset_shared with checkpointer specified as the stats type works
> +SELECT stats_reset AS checkpointer_reset_ts FROM pg_stat_checkpointer \gset
> +SELECT pg_stat_reset_shared('checkpointer');
> +SELECT stats_reset > :'checkpointer_reset_ts'::timestamptz FROM pg_stat_checkpointer;
> +SELECT stats_reset AS checkpointer_reset_ts FROM pg_stat_checkpointer \gset
>
> Note that you have forgotten to update the test of
> pg_stat_reset_shared(NULL) to check for the value of
> checkpointer_reset_ts.  I've added an extra SELECT to check that for
> pg_stat_checkpointer, and applied v8.

Oh, thanks for taking care of this. While at it, I noticed that
there's no coverage for pg_stat_reset_shared('recovery_prefetch') and
XLogPrefetchResetStats()
https://coverage.postgresql.org/src/backend/access/transam/xlogprefetcher.c.gcov.html.
Most of the recovery_prefetch code is covered with recovery/streaming
related tests, but the reset stats part is missing. So, I've added
coverage for it in the attached 0002.

--
Bharath Rupireddy
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com