Re: cpu_tuple_cost

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Josh Berkus <josh(at)agliodbs(dot)com>
Cc: Greg Stark <gsstark(at)mit(dot)edu>, David Brown <time(at)bigpond(dot)net(dot)au>, Gregory Stark <pgsql-performance(at)postgresql(dot)org>
Subject: Re: cpu_tuple_cost
Date: 2005-03-16 20:42:18
Message-ID: 8149.1111005738@sss.pgh.pa.us
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Josh Berkus <josh(at)agliodbs(dot)com> writes:
>> So what's going on with the empirically derived value of 4?

> It's not empirically derived;

Yes it is. I ran experiments back in the late 90s to derive it.
Check the archives.

Disks have gotten noticeably bigger since then, but I don't think
the ratio of seek time to rotation rate has changed much.

regards, tom lane

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