From: Michael Stone <mstone+postgres@mathom.us>
To: Luke Lonergan <LLonergan@greenplum.com>
Cc: pgsql-hackers@postgresql.org
Cc: pgsql-performance@postgresql.org
Subject: Re: [HACKERS] A Better External Sort?
Date: Wed, 05 Oct 2005 11:33:49 -0400
Message-ID: <20051005153349.GZ2241@mathom.us> (raw)
In-Reply-To: <3E37B936B592014B978C4415F90D662DE11B55@MI8NYCMAIL06.Mi8.com>
References: <3E37B936B592014B978C4415F90D662DE11B55@MI8NYCMAIL06.Mi8.com>
On Wed, Oct 05, 2005 at 11:24:07AM -0400, Luke Lonergan wrote:
>Nope - it would be disk wait.
I said I/O overhead; i.e., it could be the overhead of calling the
kernel for I/O's. E.g., the following process is having I/O problems:
time dd if=/dev/sdc of=/dev/null bs=1 count=10000000
10000000+0 records in
10000000+0 records out
10000000 bytes transferred in 8.887845 seconds (1125132 bytes/sec)
real 0m8.889s
user 0m0.877s
sys 0m8.010s
it's not in disk wait state (in fact the whole read was cached) but it's
only getting 1MB/s.
Mike Stone
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To: pgsql-performance@postgresql.org
Cc: mstone+postgres@mathom.us, LLonergan@greenplum.com, pgsql-hackers@postgresql.org
Subject: Re: [HACKERS] A Better External Sort?
In-Reply-To: <20051005153349.GZ2241@mathom.us>
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