Re: [HACKERS] A Better External Sort?

Nope - it would be disk wait.

COPY is CPU bound on I/O subsystems faster that 50 MB/s on COPY (in) and about 15 MB/s (out).

- Luke

 -----Original Message-----
From:     Michael Stone [mailto:mstone+postgres@mathom.us]
Sent:    Wed Oct 05 09:58:41 2005
To:    Martijn van Oosterhout
Cc:    pgsql-hackers@postgresql.org; pgsql-performance@postgresql.org
Subject:    Re: [HACKERS] [PERFORM] A Better External Sort?

On Sat, Oct 01, 2005 at 06:19:41PM +0200, Martijn van Oosterhout wrote:
>COPY TO /dev/null WITH binary
>13MB/s    55% user 45% system  (ergo, CPU bound)
[snip]
>the most expensive. But it does point out that the whole process is
>probably CPU bound more than anything else.

Note that 45% of that cpu usage is system--which is where IO overhead
would end up being counted. Until you profile where you system time is
going it's premature to say it isn't an IO problem.

Mike Stone


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