Re: Expose JIT counters/timing in pg_stat_statements

On Tue, Mar 8, 2022 at 4:08 AM Julien Rouhaud <rjuju123@gmail.com> wrote:

> On Mon, Mar 07, 2022 at 01:40:34PM +0100, Magnus Hagander wrote:
> >
> > I wonder if there might be an interesting middle ground, or if that is
> > making it too much. That is, we could have an
> > Option 3:
> > jit_count
> > total_jit_time - for sum of functions+inlining+optimization+emission time
> > min_jit_time - for sum of functions+inlining+optimization+emission time
> > max_jit_time - for sum of functions+inlining+optimization+emission time
> > mean_jit_time - for sum of functions+inlining+optimization+emission time
> > stddev_jit_time - for sum of functions+inlining+optimization+emission
> time
> > jit_functions
> > jit_generation_time
> > jit_inlining_count
> > jit_inlining_time
> > jit_optimization_count
> > jit_optimization_time
> > jit_emission_count
> > jit_emission_time
> >
> > That is, we'd get the more detailed timings across the total time, but
> > not on the details. But that might be overkill.
>
> I also thought about it but it seems overkill.  pg_stat_statements view is
> already very big, and I think that the JIT time should be somewhat stable,
> at
> least compared to how much a query execution time can vary depending on the
> parameters.  This approach would also be a bit useless if you change the
> costing of underlying JIT operation.
>
> > But -- here's an updated patched based on Option 2.
>
> Thanks!
>
> Code-wide, the patch looks good.  For the doc, it seems that you documented
> jit_inlining_count three times rather than documenting
> jit_optimization_count
> and jit_emission_count.
>

Oops, thanks and fixed.


I don't think we can add tests there, and having a test for every new
> counter
> being >= 0 seems entirely useless, however there should be a new test
> added for
> the "oldextversions" test to make sure that there's no issue with old SQL
> / new
> shlib compatibility.  And looking at it I see that it was already missed
> for
> version 1.9 :(
>

Indeed. Fixed here.

Michael had already applied a patch that took us to 1.10 and added that
test, so I've just updated it here. I don't think we normally bump the
version twice int he same day, so I just mergd the SQL script changes as
well.

PFA a "final" version for the CI to run.

-- 
 Magnus Hagander
 Me: https://www.hagander.net/ <http://www.hagander.net/>
 Work: https://www.redpill-linpro.com/ <http://www.redpill-linpro.com/>