On Fri, Sep 29, 2023 at 1:15 PM Daniel Gustafsson <dan...@yesql.se> wrote: > > On 28 Sep 2023, at 23:50, Alexander Korotkov <aekorot...@gmail.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?
Thank you for doing experiments on your side. I've rechecked. It appears that I didn't do enough runs, thus I didn't see the overhead as more than an error. Now, I also can confirm ~5% overhead. I spent some time thinking about how to overcome this overhead, but I didn't find a brilliant option. Previously pg_database flag was proposed but then criticized as complex and error-prone. I can also imagine shmem caching mechanism. But it would require overcoming possible race conditions between shared cache invalidation and transaction commit etc. So, that would be also complex and error-prone. Any better ideas? > 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? Fixed. > Thanks for working on this! Thank you as well! ------ Regards, Alexander Korotkov
0001-Add-support-of-event-triggers-on-authenticated-l-v42.patch
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