Re: How to improve db performance with $7K? - Mailing list pgsql-performance

From Tom Lane
Subject Re: How to improve db performance with $7K?
Date
Msg-id 29785.1113542934@sss.pgh.pa.us
Whole thread Raw
In response to Re: How to improve db performance with $7K?  (Kevin Brown <kevin@sysexperts.com>)
Responses Re: How to improve db performance with $7K?  (Kevin Brown <kevin@sysexperts.com>)
List pgsql-performance
Kevin Brown <kevin@sysexperts.com> writes:
> In the case of pure random reads, you'll end up having to wait an
> average of half of a rotation before beginning the read.

You're assuming the conclusion.  The above is true if the disk is handed
one request at a time by a kernel that doesn't have any low-level timing
information.  If there are multiple random requests on the same track,
the drive has an opportunity to do better than that --- if it's got all
the requests in hand.

            regards, tom lane

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