Re: WAL usage calculation patch

> вт, 18 февр. 2020 г. в 06:23, Thomas Munro <thomas(dot)munro(at)gmail(dot)com>:
> > On Mon, Feb 10, 2020 at 8:20 PM Craig Ringer <craig(at)2ndquadrant(dot)com> wrote:
> > > On Wed, 5 Feb 2020 at 21:36, Kirill Bychik <kirill(dot)bychik(at)gmail(dot)com> wrote:
> > > > Patch is separated in two parts: core changes and pg_stat_statements
> > > > additions. Essentially the extension has its schema updated to allow
> > > > two more fields, docs updated to reflect the change. Patch is prepared
> > > > against master branch.
> > > >
> > > > Please provide your comments and/or code findings.
> > >
> > > I like the concept, I'm a big fan of anything that affordably improves
> > > visibility into Pg's I/O and activity.
> >
> > +1
> >
> > > To date I've been relying on tools like systemtap to do this sort of
> > > thing. But that's a bit specialised, and Pg currently lacks useful
> > > instrumentation for it so it can be a pain to match up activity by
> > > parallel workers and that sort of thing. (I aim to find time to submit
> > > a patch for that.)
> >
> > (I'm interested in seeing your conference talk about that! I did a
> > bunch of stuff with static probes to measure PHJ behaviour around
> > barrier waits and so on but it was hard to figure out what stuff like
> > that to put in the actual tree, it was all a bit
> > use-once-to-test-a-theory-and-then-throw-away.)
> >
> > Kirill, I noticed that you included a regression test that is failing. Can
> > this possibly be stable across machines or even on the same machine?
> > Does it still pass for you or did something change on the master
> > branch to add a new WAL record since you posted the patch?
>
> Thank you for testing the patch and running extension checks. I assume
> the patch applies without problems.
>
> As for the regr test, it apparently requires some rework. I didn't pay
> attention enough to make sure the data I check is actually meaningful
> and isolated enough to be repeatable.
>
> Please consider the extension part of the patch as WIP, I'll resubmit
> the patch once I get a stable and meanngful test up. Thanks for
> finding it!
>

I have reworked the extension regression test to be more isolated.
Apparently, something merged into master branch shifted my numbers.

PFA the new patch. Core part didn't change a bit, the extension part
has regression test SQL and expected log changed.

Looking forward for new comments.