| From: | Daniel Gustafsson <daniel(at)yesql(dot)se> |
|---|---|
| To: | Alexander Korotkov <aekorotkov(at)gmail(dot)com> |
| Cc: | Mikhail Gribkov <youzhick(at)gmail(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Greg Nancarrow <gregn4422(at)gmail(dot)com>, Ivan Panchenko <wao(at)mail(dot)ru>, Teodor Sigaev <teodor(at)sigaev(dot)ru>, Ibrar Ahmed <ibrar(dot)ahmad(at)gmail(dot)com>, vignesh C <vignesh21(at)gmail(dot)com>, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> |
| Subject: | Re: On login trigger: take three |
| Date: | 2023-09-29 10:15:30 |
| Message-ID: | 506F25C0-14F7-46FC-AF48-3DBA05550A19@yesql.se |
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| Lists: | pgsql-hackers |
> On 28 Sep 2023, at 23:50, Alexander Korotkov <aekorotkov(at)gmail(dot)com> wrote:
> I don't think I can reproduce the performance regression pointed out
> by Pavel Stehule [1].
> I can't confirm the measurable overhead.
Running the same pgbench command on my laptop looking at the average connection
times, and the averaging that over five runs (low/avg/high) I see ~5% increase
over master with the patched version (compiled without assertions and debug):
Patched event_triggers on: 6.858 ms/7.038 ms/7.434 ms
Patched event_triggers off: 6.601 ms/6.958 ms/7.539 ms
Master: 6.676 ms/6.697 ms/6.760 ms
This is all quite unscientific with a lot of jitter so grains of salt are to be
applied, but I find it odd that you don't see any measurable effect. Are you
seeing the same/similar connection times between master and with this patch
applied?
A few small comments on the patch:
+ prevent successful login to the system. Such bugs may be fixed by
+ restarting the system in single-user mode (as event triggers are
This paragraph should be reworded to recommend the GUC instead of single-user
mode (while retaining mention of single-user mode, just not as the primary
option).
+ Also, it's recommended to evade long-running queries in
s/evade/avoid/ perhaps?
Thanks for working on this!
--
Daniel Gustafsson
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