| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Simon Riggs <simon(dot)riggs(at)enterprisedb(dot)com> |
| Cc: | Michail Nikolaev <michail(dot)nikolaev(at)gmail(dot)com>, Andrey Borodin <x4mmm(at)yandex-team(dot)ru>, Kyotaro Horiguchi <horikyota(dot)ntt(at)gmail(dot)com>, Alexander Korotkov <aekorotkov(at)gmail(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, reshkekirill <reshkekirill(at)gmail(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Slow standby snapshot |
| Date: | 2022-11-15 22:53:27 |
| Message-ID: | 1235928.1668552807@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Simon Riggs <simon(dot)riggs(at)enterprisedb(dot)com> writes:
> I've cleaned up the comments and used a #define for the constant.
> IMHO this is ready for commit. I will add it to the next CF.
I looked at this a little. It's a simple enough patch, and if it
solves the problem then I sure like it better than the previous
ideas in this thread.
However ... I tried to reproduce the original complaint, and
failed entirely. I do see KnownAssignedXidsGetAndSetXmin
eating a bit of time in the standby backends, but it's under 1%
and doesn't seem to be rising over time. Perhaps we've already
applied some optimization that ameliorates the problem? But
I tested v13 as well as HEAD, and got the same results.
regards, tom lane
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