From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
---|---|
To: | Peter Geoghegan <pg(at)heroku(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: | 2016-04-08 06:08:29 |
Message-ID: | CA+TgmoaHWeromNxV7Spaej9EMXY3p1ONvU3RWnOPCM-R=OinOQ@mail.gmail.com |
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Lists: | pgsql-hackers |
On Tue, Apr 5, 2016 at 1:05 PM, Peter Geoghegan <pg(at)heroku(dot)com> wrote:
> 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.
Yeah. I've committed the patch now, with some cosmetic cleanup.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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