| From: | Peter Geoghegan <pg(at)heroku(dot)com> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
| Cc: | Dilip Kumar <dilipbalaut(at)gmail(dot)com>, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, Petr Jelinek <petr(at)2ndquadrant(dot)com>, Jim Nasby <Jim(dot)Nasby(at)bluetreble(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Andres Freund <andres(at)2ndquadrant(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Relation extension scalability |
| Date: | 2016-04-05 17:05:41 |
| Message-ID: | CAM3SWZSFaj4ru8aFDwOv-piFMSqBtsK9tspmLP11UXoexumDVQ@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Tue, Apr 5, 2016 at 10:02 AM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> So the first thing here is that the patch seems to be a clear win in
> this test. For a single copy, it seems to be pretty much a wash.
> When running 4 copies in parallel, it is about 20-25% faster with both
> logged and unlogged tables. The second thing that is interesting is
> that we are getting super-linear scalability even without the patch:
> if 1 copy takes 20 seconds, you might expect 4 to take 80 seconds, but
> it really takes 60 unpatched or 45 patched. If 1 copy takes 30
> seconds, you might expect 4 to take 120 seconds, but in really takes
> 105 unpatched or 80 patched. So we're not actually I/O constrained on
> this test, I think, perhaps because this machine has an SSD.
It's not unusual for COPY to not be I/O constrained, I believe.
--
Peter Geoghegan
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