Re: 7.2.1 optimises very badly against 7.2

Tom Lane wrote (snipped)
>There have been a couple of rounds of
>pgsql-hackers discussion about whether to lower the default value of
>random_page_cost, but so far no one has done any experiments that
>would be needed to establish a good new value. (The current default
>of 4.0 is based on some old experiments I did

4.0 seems like a pretty reasonable default setting.

I had the opportunity to measure approximate random_page_cost for a
number of configurations recently whilst doing some file system
benchmarking:

Rough Config Random_page_cost
----------------------------------------------------------------
Sun E220 Solaris 8 SAN RAID 5 6
Cyclone Linux,3Ware 7850 4xATA-133 RAID 5 40
Cyclone Linux 1xATA 133 10

Given the wide variation obtainable ... I cant see any reason to move
away from 4.0.

regards

Mark

P.s : I used these to do the measurements -

http://homepages.slingshot.co.nz/~markir/tar/benchtool/benchtools-0.9.1.tar.gz

and if anyone knows how to enable largefile support on Linux in a
cleaner way than I did, feel free to let me know !