Re: Index Scans become Seq Scans after VACUUM ANALYSE

On Wed, 2002-04-17 at 19:43, Tom Lane wrote:
> Hannu Krosing <hannu(at)tm(dot)ee> writes:
> > OTOH, it is also important where the file is on disk. As seen from disk
> > speed test graphs on http://www.tomshardware.com , the speed difference
> > of sequential reads is 1.5 to 2.5 between inner and outer tracks.
>
> True. But if we use the same test file for both the sequential and
> random-access timings, hopefully the absolute speed of access will
> cancel out. (Again, it's the sort of thing that could use some
> real-world testing...)

Not so sure about that. Random access basically measures latency,
sequential access measures transfer speed. I'd argue that latency is
more or less constant across the disk as it depends on head movement and
the spindle turning.

cheers
-- vbi