| From: | Greg Smith <greg(at)2ndquadrant(dot)com> |
|---|---|
| To: | Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com> |
| Cc: | Robert Haas <robertmhaas(at)gmail(dot)com>, david(at)lang(dot)hm, Vitalii Tymchyshyn <tivv00(at)gmail(dot)com>, Kenneth Marshall <ktm(at)rice(dot)edu>, Jon Nelson <jnelson+pgsql(at)jamponi(dot)net>, Andrew Dunstan <andrew(at)dunslane(dot)net>, Bruce Momjian <bruce(at)momjian(dot)us>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Craig Ringer <craig(at)postnewspapers(dot)com(dot)au>, "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org> |
| Subject: | Re: [HACKERS] Slow count(*) again... |
| Date: | 2011-02-05 08:49:05 |
| Message-ID: | 4D4D0F01.6070407@2ndquadrant.com |
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| Thread: | |
| Lists: | pgsql-hackers pgsql-performance |
Scott Marlowe wrote:
> With a 24 drive RAID-10 array that can read at ~1GB/s I am almost
> always CPU bound during copies. This isn't wholly bad as it leaves
> spare IO for the rest of the machine so regular work carries on just
> fine.
>
And you don't need nearly that much I/O bandwidth to reach that point.
I've hit being CPU bound on COPY...FROM on systems with far less drives
than 24.
--
Greg Smith 2ndQuadrant US greg(at)2ndQuadrant(dot)com Baltimore, MD
PostgreSQL Training, Services, and 24x7 Support www.2ndQuadrant.us
"PostgreSQL 9.0 High Performance": http://www.2ndQuadrant.com/books
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