Horton

Re: [HACKERS] Slow count(*) again...

Greg Smith <greg@2ndquadrant.com>

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From: Greg Smith <greg@2ndquadrant.com>
To: Scott Marlowe <scott.marlowe@gmail.com>
Cc: Robert Haas <robertmhaas@gmail.com>, david@lang.hm, Vitalii Tymchyshyn <tivv00@gmail.com>, Kenneth Marshall <ktm@rice.edu>, Jon Nelson <jnelson+pgsql@jamponi.net>, Andrew Dunstan <andrew@dunslane.net>, Bruce Momjian <bruce@momjian.us>, Tom Lane <tgl@sss.pgh.pa.us>, Craig Ringer <craig@postnewspapers.com.au>, "pgsql-performance@postgresql.org" <pgsql-performance@postgresql.org>
Date: 2011-02-05T08:49:05Z
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@2ndQuadrant.com   Baltimore, MD
PostgreSQL Training, Services, and 24x7 Support  www.2ndQuadrant.us
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