| From: | Michael Paquier <michael(at)paquier(dot)xyz> |
|---|---|
| To: | Julien Rouhaud <rjuju123(at)gmail(dot)com> |
| Cc: | Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com>, gkokolatos(at)pm(dot)me, Ranier Vilela <ranier(dot)vf(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, depesz(at)depesz(dot)com |
| Subject: | Re: Showing I/O timings spent reading/writing temp buffers in EXPLAIN |
| Date: | 2022-04-07 07:24:54 |
| Message-ID: | Yk6Rxp/vpiC0F4Uy@paquier.xyz |
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| Lists: | pgsql-hackers |
On Thu, Apr 07, 2022 at 03:14:01PM +0800, Julien Rouhaud wrote:
> Sure, but gettimeofday() has been implemented in vDSO for quite some time on
> most platforms, so it shouldn't hurt that much on mainstream platforms
> especially compared to the cost of whatever operation is actually using that
> temporary file.
>
> I don't think that having an extra GUC for temp IO is sensible, if that's why
> you're suggesting? Or are you just asking to do some benchmarking on some
> platform where getting the time is known to be slow (Windows?).
I am asking about the latter, but the former could be one solution if
the latter proves to be a problem, and this has not been discussed on
the thread yet. So, with some kind of worst-case scenario, how much
worse the performance gets once you add those extra calls when
compared to HEAD? I think that we'd better be careful with any
additions of INSTR_TIME_SET_CURRENT().
--
Michael
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