Command-line Yaouh! clone

[Helge Hafting]

Risto H. Kurppa wrote:
> On Thu, Apr 23, 2009 at 11:40 AM, Carlo Minucci <gecco at napodano.com> wrote:
>> which funcionality do you want on yaouh? :)
> 
> 
> These here sound good to me to have around (in Yaouh, too)
> * skipping files modified recently

How recent would that be?
I run yaouh to get the latest tiles where I have updated the map. Of 
course, this is often the same tiles as I refreshed a couple of days 
earlier. So I think this has to be optional. Some kind of uses need to 
check fairly new tiles.

> * forcing download empty tiles
What does that mean?

> 
> Does someone actally know how much load it creates on (new :) OSM
> servers to update X mb of tiles with y% to be updated? Are there still
> ways to decrease this?

A tile tends to be 10-30kB. Perhaps 20kB on average? A header check is 
about 100 byte.

So X MB of tiles is about 1000X/20=50X tiles. All 50X tiles get checked, 
so 50X*100 byte is about 5X kB.

Of these 50X tiles, y% gets updated, and is on average 20kB.
so, 50X*y/100*20kB = 10Xy kB.

So with these numbers, you get 5X+10Xy kB or (5+10y)X kB to transfer.

Helge Hafting