Re: cost_nonsequential_access()

On Tue, 08 Jun 2004 11:13:43 -0400, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>This patch seems to do considerably more violence to the equations than
>is needed to cover that oversight, though.  The old behavior was
>intentionally nonlinear in relsize; this is not.

The comment says "entirely ad-hoc" and I didn't see a particular reason
why the lower half should be nonlinear in relsize while the upper half
is linear in 1/relsize.  So I opted for the "more esthetic" symmetrical
function.  :-)

http://www.pivot.at/pg/costsize.jpg original
http://www.pivot.at/pg/costsize_2.jpg nonlinear/linear
http://www.pivot.at/pg/costsize_3a.jpg nonlinear
http://www.pivot.at/pg/costsize_3b.jpg linear

I don't have a strong opinion for either relsize or relsize^2.  So
please add " * relsize" or " / relsize" as appropriate before you apply
(if you intend to apply).

Servus
 Manfred