Re: Script to compute random page cost

On Mon, 2002-09-09 at 02:13, Bruce Momjian wrote:
> 
> OK, turns out that the loop for sequential scan ran fewer times and was
> skewing the numbers.  I have a new version at:
> 
>     ftp://candle.pha.pa.us/pub/postgresql/randcost
> 
> I get _much_ lower numbers now for random_page_cost.

The current script pulls way more data for Sequential scan than random
scan now.

Random is pulling a single page (count=1 for dd) with every loop. 
Sequential does the same number of loops, but pulls count > 1 in each.

In effect, sequential is random with more data load -- which explains
all of the 0.9's.

 Rod Taylor