Re: RFC: replace pg_stat_activity.waiting with something more descriptive

On 9 March 2016 at 13:31, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:

> On Fri, Mar 4, 2016 at 7:11 PM, Alexander Korotkov <aekorotkov(at)gmail(dot)com>
> wrote:
> >
> >>
> >> If yes, then the only slight worry is that there will lot of repetition
> in wait_event_type column, otherwise it is okay.
> >
> >
> > There is morerows attribute of entry tag in Docbook SGML, it behaves
> like rowspan in HTML.
> >
>
> Thanks for the suggestion. I have updated the patch to include
> wait_event_type information in the wait_event table.
>
> As asked above by Robert, below is performance data with the patch.
>
> M/C Details
> ------------------
> IBM POWER-8 24 cores, 192 hardware threads
> RAM = 492GB
>
> Performance Data
> ----------------------------
> min_wal_size=15GB
> max_wal_size=20GB
> checkpoint_timeout =15min
> maintenance_work_mem = 1GB
> checkpoint_completion_target = 0.9
>
>
> pgbench read-only (median of 3, 5-min runs)
>
> clients BASE PATCH %
> 1 19703.549206 19992.141542 1.4646718364
> 8 120105.542849 127717.835367 6.3380026745
> 64 487334.338764 495861.7211254 1.7498012521
>
>
> The read-only data shows some improvement with patch, but I think this is
> mostly attributed to run-to-run variation.
>
> pgbench read-write (median of 3, 30-min runs)
>
> clients BASE PATCH %
> 1 1703.275728 1696.568881 -0.3937616729
> 8 8884.406185 9442.387472 6.2804567394
> 64 32648.82798 32113.002416 -1.6411785572
>
>
> In the above data, the read-write data shows small regression (1.6%) at
> higher client-count, but when I ran individually that test, the difference
> was 0.5%. I think it is mostly attributed to run-to-run variation as we see
> with read-only tests.
>
>
> Thanks to Mithun C Y for doing performance testing of this patch.
>
> As this patch is adding 4-byte variable to shared memory structure PGPROC,
> so this is susceptible to memory alignment issues for shared buffers as
> discussed in thread [1], but in general the performance data doesn't
> indicate any regression.
>
> [1] -
> http://www.postgresql.org/message-id/CAA4eK1+ZeB8PMwwktf+3bRS0Pt4Ux6Rs6Aom0uip8c6shJWmyg@mail.gmail.com
>
>
The new patch looks fine with regards to grammar and spelling.

However, the new row-spanning layout isn't declared correctly as you've
over-counted by 1 in each morerows attribute, possibly because you equated
it to the rowspan attribute in html, which will add one above whatever you
specify in the document. "morerows" isn't the total number or rows, but
how many more rows in addition to the current one will the row span.

And yes, as Robert mentioned, please can we remove the "A server process
is" repetition?

Thom