[OSM-dev] Daily Diff parsing - tile expiring

Erik Johansson erjohan at gmail.com
Thu Aug 21 01:04:39 BST 2008

On Thu, Aug 21, 2008 at 1:42 AM, Frederik Ramm <frederik at remote.org> wrote:
> Hi,
>> I think that adding the Lat/Lon tag to node references in the ways is not an
>> option since it would require a huge amount of queries on the database when
>> creating the diffs. The positive side of this would that it would only have
>> to be done once.
> If you are happy with supporting only zoom level 16 granularity, you can
> store the tile x and tile y coordinates for each node, that's only 4
> bytes per node.

According to JonB[1] there have been about 84 Million tiles requested
the last 6 months, this is the break down of how many tiles you can
invalidate by using tileposition. Example: at zoom 16 you would get
54% less rerenders, if I haven't done this all wrong.

Doesn't seem that costly to spend 300M*18bit*2=1,4GB and get 100%.

Zoom| % of all tiles in this zoom an above
11	5.22%
12	8.22%
13	13.45%
14	23.26%
15	39.55%
16	54.57%
17	82.92%
18	100.00%

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